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SUMMARY OF PhD THESIS Ing. George Călin Roiban
0
Ing. GEORGE - CĂLIN ROIBAN
SUMMARY OF PhD THESIS
CONTRIBUTIONS TO THE IMPROVEMENT OF POST-EMERGENT WEED CONTROL SYSTEM
IN CORN CROP
Scientific coordinator Prof. univ. dr. ing. PETRU GUŞ
CLUJ-NAPOCA 2010
UNIVERSITY OF AGRICULTURAL SCIENCES AND VETERINARY MEDICINE
CLUJ-NAPOCA DOCTORAL SCHOOL
FACULTATY OF AGRICULTURE
SUMMARY OF PhD THESIS Ing. George Călin Roiban
1
CONTRIBUTIONS TO THE IMPROVEMENT OF POST-EMERGENT WEED CONTROL SYSTEM
IN CORN CROP
As agriculture developed, the weed categories continuously diversify and adapted to
new conditions of agricultural technique. The result of these permanent adjustments is
observed today in the great survival capacity of weeds, and in the dynamic within certain
species communities; this dynamic is put in evidence by more adapted biotypes, by the
continuous modification of quantitative and qualitative structure of weeding, by including
new species from spontaneous local flora or from other geographical areas.
Having as pre-requisite the efficient control of weed, we consider very necessary the
knowledge of all elements part of the process.
Corn, as the main cultivated plant in the Transylvanian agriculture exploitations,
remains a preoccupation of scientists to permanently improve the culture technologies or
adapt the technology to the modifications occurred in the corn crop habitat, in the specific
machinery system or in the economic interests of this crop.
The corn particular sensitivity to weeding is an open field for herbology research and
for the study of corn crop weed control, in order to find the adequate solutions for every
homogenous ecological area, solutions that will give the effective answer to reduce the
weeding under the damaging level and to farmers’ economic effort.
The new obligations imposed by the European legislation in the field of environment
protection, certified by the modern techniques of plant protections, justify the selection of
the research theme for the PhD thesis, due to the following aspects:
corn crop is still one of the main agriculture crops at national, European and world wide
level;
crop sensitivity to weeding enforces the weed control by effective and rapid methods;
elimination of numerous herbicidal active substances with pre-emergent application
from the approved for use list;
ecological impact with low risk in the case of post-emergent chemical control;
SUMMARY OF PhD THESIS Ing. George Călin Roiban
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Possibility of combining the post-emergent methods for weed control with indirect
preventive or agrotechnical methods in order to obtain an integrated system for weed
control in corn crop, economically and ecologically efficient.
Because the corn crop is cultivated on a very wide surface in different pedo-climatic
areas, the weed infestation differs very much in the country. Variations are bigger if we
observe the ratio of certain weed species towards other, the monocotyledonated species
towards the dicotyledonated, the annual towards the perennial etc.; thus, the selection of the
right strategy for weed control has to be made in the real local conditions.
From the considerations that:
the characteristic weed flora for corn is variable in the territory;
the climatic conditions are variable as well;
the herbicide effect can vary – is related to their adequate selection, their
application technique and the weather;
safety of the agro-ecosystem, animal and human health are also variable, in
relation to many natural and anthropic factors, among other things being the right
approach of weed control methods in the agriculture crops;
the profit of corn crop farmers varies depending on the fact that the technological
steps of crop are correctly applied and on the local conditions
By the research carried out for this thesis, I envisage to clarify certain aspects
concerning the specificity of corn crop weeding in Alba County (commune of Noşlac), the
efficacy of the post-emergence weed control strategies for corn crop, the selectivity of
chemical recipes for corn crop cultivated in this area and the preservation of ecological
balance.
SUMMARY OF PhD THESIS Ing. George Călin Roiban
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THE PURPOSE OF THE RESEARCH
The main purpose of the research studies is: to elaborate the strategies for post-
emergent weed control in corn crop, which are optimal from technological, economical and
ecological point of view, for the high meadow area of Alba County. In order to achieve this
goal, there is necessary to cover three essential steps, every one with their own specific
scientific and applicative objectives.
These three steps are determined by the three components needed to making efficient
the results of post-emergent weed control in corn crop and the applicability of those results
to extension in agriculture production of the area. Thus, the research made during 2004-
2007 is framed in the following three stages:
⇒ Establishing the competition between weed and corn plants in the specific
experimental conditions;
⇒ Elaboration the strategies of post-emergence weed control for corn crop in high
meadow areas from Alba county;
⇒ Setting the minimal elements for research extension
THE OBJECTIVES OF THE RESEARCH
The first stage of the research studies - establishing the competition between weed
and corn plants in the experimental conditions of Noşlac – envisage the following study
objectives:
Inventory of weeding degree of corn crop from Noşlac area, Alba County.
Establishing the “problem: weed species for this crop culture;
Establishing the correlations between the weeding level of the area crop culture
and the production;
Establishing the correlations between the weeding level of the crop culture and
climate factors of the research years;
Establishing the fluctuation of weeding level during the 4 research years;
SUMMARY OF PhD THESIS Ing. George Călin Roiban
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The second stage of the research studies - elaboration the strategies of post-
emergence weed control for corn crop in high meadow areas from Alba County - envisages
the following study objectives:
Stating the basic elements for elaboration of the strategies of post-emergence
weed control
Testing certain chemical and mixed strategies of post-emergence weed control for
corn crop;
Elaboration of strategies of post-emergence weed control for corn crop in high
meadow areas from Alba county, optimal from technological, economical and
ecological point if view
The third stage of the research studies - setting the minimal elements for research
extension - envisages the following study objectives:
Establishing the economic efficiency of weed control technology with associated
herbicides – single treatment;
Establishing the economic efficiency of weed control technology with associated
herbicides –two treatments;
Establishing the economic efficiency of weed control technology with associated
herbicides – single treatment + mechanical hoeing
Establishing the economic efficiency of weed control technology with total
herbicides applied in triticale crop stubble field + single post-emergent treatment
with associated or complex herbicides.
SUMMARY OF PhD THESIS Ing. George Călin Roiban
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THE EXPERIMENTAL DEVICE
The researches on improving the strategies for post-emergence weed control in corn
crop developed in a 4 years period: 2004-2007, in a private property field of Noşlac
commune, Alba County, within the framework of bifactorial stationary experiments, settled
after the randomized blocks method, with 28 variants in four repetitions. The total area
surface was 30 sq meters.
The experimental factors and their graduations are:
A. Weed control method: 28 graduations grouped in 4 control technologies and 2
witnesses:
a1 = classical weed control, 3 manual hoeing – control variant no 1
a2 = no weed control – control variant no 2
a3 – a10 = chemical weed control, single post-emergence treatment with
associated herbicide
a11 – a16 = chemical weed control, 2 post-emergence treatments with fractioned
dosage: an early first one (2-3 corn leaves); the second one at 5-6 corn leaves
stage
a17 – a22 = mixed weed control, early treatment (2-3 corn leaves) with associated
or complex herbicides, followed by mechanical hoeing,
a23 – a28 = 2 years chemical weed control, treatment with total herbicides in
triticale stubble field + single treatment with associated herbicides at 5-6 corn
leaves stage.
B. Experimental years: 4 graduations,
b1 = 2004
b2 = 2005
b3 = 2006
b4 = 2007
In order to establish the efficacy in post-emergence weed control, 11 herbicide
products were tested, having different active substances: foramsulfuron + isoxadifen ethyl,
SUMMARY OF PhD THESIS Ing. George Călin Roiban
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rimsulfuron, mesotrione, prosulfuron + primsulphuron, 2.4D acid + MCPA+ clopyralid,
bromoxynil + 2.4D (ester), florasulam+ 2,4 D (EHE), bromoxynil octanoate.
The corn cultivation technology in the experimental field comprises:
3 years crop rotation: autumn triticale – corn – potato + sugar beet + vegetables (fig. 1);
Differentiated working system function of applied weed control variants, as follows:
o For the 4 treatment variants in
previous crop stubble field:
triticale harvest (last decade of
July) - stubble field herbicide
application on all area, with
LEONE 36 SL: 4 l/ ha, 14
days after harvesting – (30 t/ha
manure applied in the second
decade of September, in 2003
– rotation 2 and 3 - and in
2004 – rotation 2) – autumn
ploughing at 25 cm depth, in
the last decade of September
or first decade of October – single rotary harrow passing
o For the 4 treatment variants in previous crop stubble field: triticale harvest (last
decade of July) - stubble field herbicide application all over the area, with LEONE 36
SL: 4 l/ ha, 14 days after harvesting – (30 t/ha manure applied in the second decade
of September, in 2003 – rotation 2 and 3 - and in 2004 – rotation 2) - autumn
ploughing at 25 cm depth, in the last decade of September or first decade of October
– single rotary harrow passing
GDU 3,4 (second decade of April) – complex fertilisation – starter fertilisation Cu
N40P40 – single seedbed combination passing in the seeding day (third decade of
April) – seeded with SPC 6 – post-emergence herbicide application + first foliar
fertilisation (stage 5-6 corn leaves) – second foliar fertilisation (at ear corn formation)
– harvest (first decade of October)
The first cycle of the rotation The second cycle of the rotation
Fig. 1. The crop rotation
Anul
2004 2005 2006 2007
Rotation 1
triticale corn Potato+
Sugarbeet+ vegetable
triticale
Rotation 2
corn Potato+
Sugarbeet+ vegetable
triticale corn
Rotation 3
Potato+
Sugarbeet+ vegetable
triticale corn Potato+
Sugarbeet+ vegetable
SUMMARY OF PhD THESIS Ing. George Călin Roiban
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o For variants without stubble field herbicide application: triticale harvest (third decade
of July) – remove the stubble field by superficial ploughing (immediately after
harvest) – single disk passing in the first decade of September - 30 t/ha manure
applied in the second decade of September, in 2003 – rotation 2 and 3 - and in 2004 –
rotation 2 – autumn ploughing (first decade of October) – single rotary harrow in
spring (first decade of April) – mineral fertilisation (second decade of April) – single
seedbed combination passing the day before seeding – seeding (third decade of
April) – first hoeing in the 3 hoeing witness variant and post-emergence herbicide
application (second decade of May) – second hoeing in the 3 hoeing witness variant
and post-emergence herbicide application + first foliar fertilisation, at 5-6 corn leaves
stage – third hoeing in the 3 hoeing witness variant and first in the variants with
hoeing after application of associated or complex herbicides (first or second decade
of June) – the second foliar fertilisation - harvest
Fertilisation:
o organic- with fermented manure 30 to/ha starting in autumn 2003 – rotations 2
and 3 – and finishing in autumn 2004 (rotation 1), so that every rotation was
organic fertilised;
o mineral: 2 fractions: first - NPK with ratio formula 15:15:0: - at germination bed
preparation is assured a N40P40 dosage; the second at 6-8 leaves stage with
ammonium nitrate, being assured a total dosage of N70P40K0;
o foliar: 2 fractions of Murtonik 20:20:20 Me: first – at the same time with the
post-emergence herbicide application at 5-6 leaves stage, 2 l/ha dosage; the
second - at ear corn formation, the same dosage.
The field where the experimental plot is organized is a class I quality type, with 86
bonitation points. Soil is an aluviosol calcaric molic coluvic soil type, with a good fertility,
humus content of 3.84% in the first 60 cm, being assured a humus reserve of 161-200 t/ha.
Content of nutritive elements is different in the soil profile, corresponding to an average
supply of total nitrogen, very good supply of potassium and weak supply in phosphorous.
Chemically speaking, the only intervention needed is completion of P reserve.
SUMMARY OF PhD THESIS Ing. George Călin Roiban
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The thermal and precipitation regime during the corn vegetation period was different in
the experimental 4 years, thus the spring and development conditions of weed and the spring and
development conditions of corn crop were also different.
Year 2004 was a relatively normal year compared to multi-annual average values,
during the vegetative period of corn crop being registered average thermal deviations of
+0,58 oC, with significant deviations registered in April (+1,0 oC) and June (+1,6 oC) and
precipitation deviations of +62,2 mm. The positive thermal and negative precipitation
deviations were a surprise for the start of corn crop (May and beginning of June), thus
being felt in the weed competition but also the level of production.
Year 2005 was an exceptional year from climatic point of view, being characterised
as extremely rainy and warm (+ 1,2 oC and + 194 mm compared to multi-annual average
values). The corn vegetation period was warm (+0,95 oC compared to m.a.a. values) and
rainy, especially in April, May, August and September; during the whole period of
vegetation a plus of 167,1mm was registered. Over all, the agricultural year 2005 was a
year with pronounced weeding potential.
Year 2006 was a less warm year, compared with the previous years (the annual
average deviation was +0,90C) and less rainy, the sum of precipitations was close to multi-
annual average value (+34,1mm), but very moody, being considered as a year less
favourable for the corn crop start and with negative influence of level of production, but
significant influence, both positive and negative on weeding. Thus, the corn vegetation
period (April-September 2006) can be appreciated as warm (the positive deviation being of
1,10C). The months when significant positive deviations compared to m.a.a. values were
registered were April (+2,20C) and May (+1,9 0C). Low precipitations during April –
September 2006 overcome the normal value by 50,1 mm, which is a deviation much
smaller then the previous years, but with very large fluctuations in precipitations during
corn vegetative period. April was very rainy the first two decades, followed bay a dry May,
when corn crop suffered a little. The rains dropped in the second part of May saved the corn
crop, which passed in optimal conditions the vegetative stages of this period. The dryness in
the first half of May negatively influenced the spring and development of corn crop, but at
the same time, influenced the weeding level, which was lower.
SUMMARY OF PhD THESIS Ing. George Călin Roiban
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Year 2007 was a very warm (the m.a.a. deviation was +2,20C) and rainy at the same
time; the sum of precipitations overcome the m.a.a. by 104,4 mm, but the their repartition
was less good for the corn crop. Analyzing the vegetative period of corn in 2007 showed
that was not a very good year for corn crop. The excessive dryness during June and
moderate in July defined the negative influence of this year climate on corn crop yield.
In order to improve the system of post-emergence weed control in corn crop was
important to proper organise the information system, the research data collection and to
make the following determinations:
Determinations of corn specific weeding characteristics in the studied area:
determination of floral compositions, determination of annual and average weeding
degree (number and weight), determination of annual weight of weed species and
establishing their average weight, establishing the weeding fluctuations specific to the
experimental 4 years, establishing the weed species problematic for corn crop cultivated
in the high meadow area of Alba County (the Noşlac area) and not in the last –
establishing the correlations between level of corn productions and level of weeding;
Determination of tested weed control variants efficacy, namely 4 different post-
emergence control technologies: determination of weed control degree, assured in the
first 50-60 days of corn vegetation (corresponding to the 30 days after first herbicide
application determination), annual and 4 years average values; determination of weed
control degree, assured after 65-70 days of corn vegetation period, for every tested
variant (corresponding to the 45 days after first herbicide application determination),
annual and 4 years average values; comparative determinations between the 4 tested
weed control technologies, annual and 4 years average values;
Determination of level of obtained grain productions: annual and 4 experimental years
average determination, comparative analyses of tested weed control variants and of
tested weed control technologies;
Determination of economic efficiency: calculation of production value, production
expenses, total profit, and rate of profit for every tested weed control variant and their
comparative analysis; also, calculation of average profit and average rate of profit for
the tested 4 weed control technologies and comparative analysis;
SUMMARY OF PhD THESIS Ing. George Călin Roiban
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RESULTS OBTAINED
The data included in the PhD thesis, obtained from the experimental field during
2004-2007 and interpreted, accordingly to the rules of statistical processing and
interpretation, make possible the formulation of certain conclusions and recommendations
concerning “the improvement of post-emergence weed control system in corn crop”.
Based on the experimental results, I formulated the following opinions, with the
mention that by these results I tried to add something to the knowledge in the field of
weeding specific to the corn crop cultivated in similar areas and of present weed control
methods, specifically their influence on economic indices and the possibility of extension .
PARTIAL RESULTS CONCERNING THE CHARACTERISTICS OF WEEDING IN CORN CROP CULTIVATED
IN NOŞLAC COMMUNE AREA, ALBA COUNTY
The specific weeding of corn crop, in conditions of experimental field from Noşlac,
determined in the 4 years of culture (2004, 2005, 2006 and 2007) reveals a diversified
floristic composition, comprised of species from all four representative groups: annual
monocotyledonous, perennial monocotyledonous, annual dicotyledonous and perennial
dicotyledonous.
The total number of species determined in corn crop during the four experimental
years was 23 (2 annual monocotyledonous, 1 perennial monocotyledonous, 14 annual
dicotyledonous and 6 perennial dicotyledonous), and the annual floristic composition of
corn weed comprises between 18 and 20 species, depending on the year.
The average weeding degree during the research period is very high, around 101,7
plants/sq.m.
The coverage degree of soil with weed at the beginning of corn vegetative period,
calculated as an 4 years average, is appreciated at 26% - a high value, considering the period
in discussion (15-20 days after the spring of corn crop).
In every one of the 4 experimental years, the competition between weed species was
high during the whole period of corn vegetation, the soil potential for weeding being
relatively high, and the climatic conditions being favourable for vegetative development of
weed species and even for late infestations in weed control variants. The strong competition
SUMMARY OF PhD THESIS Ing. George Călin Roiban
11
of the weed species was observed especially during 2005, and the weakest competition,
established by the general weeding degree and soil coverage was linked to year 2007.
Statistically, the average weeding in the witness plots is significantly different in the
4 studied years (table 1). In year 2005 was observed an increased weeding of witness plots,
statistically very significant compared to year 2004, the increase of weeding in 2006 being
statistically distinct significant compared to year 2004, and in 2007 a decrease statistically
very significant. It can be stated that, besides the dryer climate in 2007, favourable to a
reduced weeding at the beginning of the vegetation period of corn crop, the effect of tested
4 year crop rotation could also be observed.
Table 1.
Evolution of weed growth degree during research period Noşlac, 2004-2007
Curr.no. Year Number of plants/m2
% compared to Control
Differences compared to Control (pl./m2)
Significance
1. 2004 89,00 100 Ctr. Ctr. 2. 2005 164,30 184,60 75,30 *** 3. 2006 97,00 109,00 8,00 ** 4. 2007 66,40 74,60 -22,60 ooo LSD 5% = 4,16 plante/m2
LSD1% = 6,31 plante/m2 LSD 0.1% = 10,13 plante/m2
The representative weed species is the annual monocotyledonous, representing for all
4 years an average of 48,5% from the total weed species present in corn crop. The annual
dicotyledonated species follow, with an average presence of 43,6% and the perennial
dicotyledonous, with an average weeding participation of 13,5% (fig. 2).
It cannot be minimized a certain biological group when its frequency in a hoed crop
is reduced because, by eliminating the competition of the majority group or groups (by
orienting the weed control methods towards those), the low frequency specie can launch
rapidly and enter the competition with the crop (especially when the weed seed reserve of
soil shows potential for infestation with the minority species in vegetation).
SUMMARY OF PhD THESIS Ing. George Călin Roiban
12
%/total
13,548,5
43,6
0,5
AM AD PD PM
Fig. 2. Average percent of weed groups in corn crop weed growth
(Noşlac, 2004-2007)
In the case of experimental field in Noşlac, Alba County, during the 4 years of
research, statistically, the weight of weed groups significantly modifies (fig. 3). Thus, if in
2004 the annual monocotyledonous species were dominant, significantly increase in 2005
after manure fertilisation of the corn crop and due to very favourable climatic conditions,
then in the next years show a decrease, by 2007 being statistically observed a very
significant decrease compared to the time that experiments began. At the same time there is
registered an opposite evolution for the annual dicotyledonous and perennial species. It is
remarkable that in 2007 the weight of perennial dicotyledonous species reach 20,2%
compared to their weight at the beginning of experiments (11,2%).
0
10
20
30
40
50
60
70
80
90
100
2004 2005 2006 2007
year
num
ber o
f pla
nts/
squa
re m
eter
AM AD PD
Fig.3. Frequence evolution (plants / m2) for the main three groups of weed species in corn crop (Noşlac, 2004-2007)
DL5%=3,83; DL1%=5,80; DL0,1%=9,32
Ctr
**
ooo
-
DL5%=3,46; DL1%=5,25; DL0,1%=8,43
***
**Ctr -
DL5%=2,00; DL1%=3,03 DL0,1%=4,87Ctr. ** --
SUMMARY OF PhD THESIS Ing. George Călin Roiban
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Observing the average weight of weed species within the corn crop from the research
field during the 4 years of experiments (fig. 4), the constant apparition of the weed species
in the weeding determination points and also the biological features of the weeds in what
concerns the competition potential, we can consider that 15 weed species are problematic
for the corn crop cultivated in Noşlac area, Alba county: Echinochloa crus-galli,
Chenopodium album, Amaranthus retroflexus, Setaria glauca, Cirsium arvense, Galinsoga
parviflora, Convolvulus arvensis, Sonchus arvensis, Polygonum lapathyfolium, Polygonum
persicaria, Hibiscus trionum, Agropyron repens, Xanthium strumarium, Atriplex patula şi
Chenopodium polyspermum.
%/total
37.9
12.3
8.6
4.4
2.5
2.5
2.5
2.3
2.3
16
0.6 0.50.40.3
0.3
0.32 1.2 110.9
0.90.8 ECHCG
CHEAL
AMARE
SETGL
CIRAR
GALPA
CONAR
SONAR
POLLA
POLPE
HIBTR
AGRRE
XANST
ATRPA
CHEPO
STEME
POLAV
SYMOF
LATTU
RAPRA
CHEHY
LAPCO
RUBCH Fig. 4. Average participation of weed species in corn crop weed growth
(Noşlac, 2004-2007) The negative evolution tendency of weeding characteristics, specific to the corn crop
cultivated in the studied area, can be supported or stopped by the following aspects:
o soil and climate conditions are favourable for the development of weed species
(annual and perennial) that strongly compete with the corn crop and especially for the
species with phased appearance, that practically invade the previous triticale stubble
field or the corn crop in the second part of vegetation period;
SUMMARY OF PhD THESIS Ing. George Călin Roiban
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o the massive infestation with annual mono-cotyletonated species, especially
Echinochloa crus-galli and Setaria glauca, that have already a very strong seed
reserve in soil and are species that strongly compete with other weed species, being
present the risk of their negative impact on the cultivated field;
o increase of perennial di-cotyledonated species incidence; they are dryness resistant
during the stressful periods for corn crop or other annual species, and are very hard to
control with corn selective herbicides (especially Convolvulus arvensis, Sonchus
arvensis, Cirsium arvense, Symphytum officinale, etc);
o use of weed control technologies with major impact on slowing the development of
areas occupied with dangerous species (glyphosate in previous crops stubble field);
o agriculture exploitations organisation, in the manner that the applied crop rotations
have a bigger contribution to diminishing the biological reserve of weed species in
soil and at the same time, to improving the fertility conditions of soils.
PARTIAL RESULTS CONCERNING THE EFICACY OF
POST-EMERGENCE WEED CONTROL TECHNOLOGIES IN CORN CROP
By comparing the four tested weed control technologies with the classical weed
control technology, applied in the control variant no 1 (fig. 1 and table 2), in mate matter of
efficacy in weed control in the first 50-60 days of corn vegetation, it can be concluded that:
The 2 years chemical control technology (stubble field treatment with glyphosate and a
post-emergence treatment with associated or complex herbicides) statistically presents
insignificant differences compared to the manual hoeing variant, and assured an average
control percent of 98.03;
The other control technologies have control average values that overcome 90%, but
statistically are significantly different compared to witness variant and the fourth tested
technology;
The 2 years chemical control technology with 2 post-emergence treatments in corn crop is
very close to the mixed control technology with single treatment completed with single
hoeing. To make the difference between the two, the production results and economic
efficiency must be analysed.
SUMMARY OF PhD THESIS Ing. George Călin Roiban
15
85
90
95
100
105
1 2 3 4 5 6 7 8number of variant
% c
ontro
l
V1control 1 1st technology 2nd technology 3rd technology 4th technology
Fig.5. Specific curves of average weed control degree (%) accomplished by tested
technologies in the first 50-60 days of corn vegetation (Noşlac, 2004-2007)
Table 2.
Average weed control degree accomplished in tested variants from the four tested technologies in the first 50-60 days of corn vegetation
Noşlac, 2004-2007 Specific variants for weed control technology Curr
No Weed control technology Control I-
3 manual hoeing 1 2 3 4 5 6 7 8 Avera
ge 1. Chemical: single post-
emergent treatment with associated herbicides
99.9
V3
94.3
V4
94.5
V5
94.4
V6
96.5
V7
91.3
V8
96.1
V9
96.7
V10
97.2
94.6 ooo
2. Chemical: 2 post-emergent treatments with associated herbicides in fractionated doses
99.9
V11
91.4
V12
92.8
V13
90.5
V14
92.1
V15
93.7
V16
91.9
- -
92.07ooo
3. Mixed: precocious post-emergent treatment with associated or complex herbicides followed by a mechanical weeding
99.9
V17
89.3
V18
88.8
V19
89.5
V20
94.5
V21
90.0
V22
96.1
- - 91.37ooo
4. Chemical in 2 years: glyphosate-based herbicides applied pre-crop stubble and one post-emergent treatment with associated or complex herbicides
99.9
V23
98.5
V24
98.8
V25
97.6
V26
98.0
V27
97.8
V28
97.5
- - 98.03
-
LSD (p 5%) =1.99% LSD (p 1%) =2.71% LSD (p 0.1%) =3.67%
SD Values 1,99 2,09 2,15 2,20A
A B
C
C
SUMMARY OF PhD THESIS Ing. George Călin Roiban
16
By adding another 15-20 days to the first period of study, can be concluded (table 3
and fig. 6):
The average control percent values, calculated for every technology and period, decrease
to very significant differences (statistically speaking) compared to witness technology
(three manual technologies). The chemical control technology with a single treatment
with associated herbicides assured just over 80% weed reduction, the other technologies
overcoming 90% reduction;
The glyphosate technology is surpassed (as efficacy) by the third tested technology
(single post-emergence treatment with associated or complex herbicides + a late hoeing).
Even if the percentual differences are small (average of 3,7%), they are all statistically
assured;
As the corn crop is passing through its vegetation period, the glyphosate technology
matches the technology no 2 (repeated treatments with associated herbicides, in post-
emergence):
Table 3.
Average weed control degree accomplished in tested variants from the four tested technologies after 65-75 days of corn vegetation
Noşlac, 2004-2007 Specific variants for weed control technology Curr
No Weed control technology Control I -
3 manual hoeing 1 2 3 4 5 6 7 8 Average
1. Chemical: single post-emergent treatment with associated herbicides
98.5
V3
79.5
V4
80.8
V5
81.3
V6
81.7
V7
80.1
V8
81.3
V9
81.3
V10
83
80.8ooo
2. Chemical: 2 post-emergent treatments with associated herbicides in fractionated doses
98.5
V11
90.6
V12
92.3
V13
90.5
V14
91.6
V15
92.9
V16
91.1
- -
91.5ooo
3. Mixed: precocious post-emergent treatment with associated or complex herbicides followed by a mechanical weeding
98.5
V17
91.5
V18
90.8
V19
91.8
V20
97
V21
96.1
V22
98.3
- - 94.3ooo
4. Chemical in 2 years: glyphosate-based herbicides applied pre-crop stubble and one post-emergent treatment with associated or complex herbicides
98.5
V23
91.4
V24
92.5
V25
90
V26
90.5
V27
90
V28
89.2
- - 90.6ooo
LSD (p 5%) =2.04% LSD (p 1%) =2.77% LSD (p 0.1%) =3.75%
SUMMARY OF PhD THESIS Ing. George Călin Roiban
17
75
80
85
90
95
100
1 2 3 4 5 6 7 8number of variant
% c
ontro
l
V1 control 1 1st technology 2nd technology 3rd technology 4th technology
Fig.6. Specific curves of average weed control degree accomplished by tested technologies in the first 60-75 days of corn vegetation ( Noşlac, 2004-2007)
Before corn crop harvest, the specific biomass of weed species present in the culture is
the comparing value to appreciate the general efficacy of weed control technologies. It is
remarkable that, compared to classic weed control technology, two other tested control
technologies are statistically very significant: the chemical technology with glyphosate in the
stubble field + post-emergence treatment with associated herbicide and the mixed control
technology comprising post-emergence early treatment with associated herbicides and late
mechanical hoeing (table 4).
By comparing the control degree curves of the entire vegetation period of corn crop
for the 4 tested control technologies (fig. 7), it can be noticed that there are no statistically
assured differences between 3 of them. The exception is the chemical technology with a
single treatment, which is obviously inferior. This statistically homogenisation is possible
due to specific fluctuations in weeding control of every technology during the period of
vegetation.
SD values 2,03 2,14 2,20 2,25
A B
C
C D
SUMMARY OF PhD THESIS Ing. George Călin Roiban
18
Table 4.
Average weed control degree accomplished in tested variants from the four tested technologies at the ending of corn vegetation
Noşlac, 2004-2007 Specific variants for weed control technology Curr
No Weed control technology Control I -
3 manual hoeing 1 2 3 4 5 6 7 8 Avera
ge
1. Chemical: single post-emergent treatment with associated herbicides
88.3
V3
67.3
V4
77.8
V5
72.0
V6
77.7
V7
73.4
V8
78.3
V9
74.9
V10
77.5
74.4 ooo
2. Chemical: 2 post-emergent treatments with associated herbicides in fractionated doses
88.3
V11
78.2
V12
82.3
V13
77.6
V14
81.3
V15
84.1
V16
80.0
- -
80.6 ooo
3. Mixed: precocious post-emergent treatment with associated or complex herbicides followed by a mechanical weeding
88.3
V17
80.4
V18
78.5
V19
81.3
V20
86.8
V21
84.2
V22
88.0
- - 83.2o
4. Chemical in 2 years: glyphosate-based herbicides applied pre-crop stubble and one post-emergent treatment with associated or complex herbicides
88.3
V23
86.5
V24
89.0
V25
82.6
V26
84.2
V27
79.1
V28
78.6
- - 83.3o
LSD (p 5%) =4.06% LSD (p 1%) =5.51% LSD (p 0.1%) =7.48%
65
70
75
80
85
90
1 2 3 4 5 6 7 8number of variant
% c
ontro
l
V1 control technology 1 technology 2 technology 3 technology 4
Fig.7. Specific curves of average weed control degree accomplished by tested technologies
at the ending of corn vegetation (Noşlac, 2004-2007)
SD values 4,05 4,26 4,38 4,48
A B
B
B
C
SUMMARY OF PhD THESIS Ing. George Călin Roiban
19
Compared and analyzed between them, the control degree diagrams for every of the
three periods of determination, specific to the four weed control technologies in corn crop
(fig. 8, 9, 10 and 11) show differences between the technologies, namely the fields limited
by the control degrees on every determination period and the whole vegetation period of
corn.
For the first technology tested for all 8 control variants, we can observe the obvious
reduction of the second moment observation area (45 days after herbicide treatment)
corresponding to a 65-75 days interval in the vegetation period of corn, compared to the first
observation moment (corresponding to first 50-60 days of corn vegetation). Also, the area
corresponding to the third observations moment for control degree (end of vegetation period
of corn crop) is much diminished. Therefore, the good and very good weed control assured
by this chemical technology is very short in time.
% of weed control
94,3
94,5
99,9
94,4
96,5
91,3
96,1
96,7
97,2
79,5
80,8
98,5
81,3
81,780,1
81,3
81,3
83
67,3
77,8
72
84,8
77,773,4
78,3
74,9
77,5
60
65
70
75
80
85
90
95
100V1
V3
V4
V5
V6V7
V8
V9
V10
30 days45 daysat the harvest
Fig. 8. Weed control degree accomplished by first technology variants in
the three moments of determinations (Chemical weed control: single post-emergent treatment with associated herbicides)
LSD (p5%) = 4.85 % LSD (p1%) = 6.67 % LSD (p0.1%) = 9.19%
Ctr.
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oo
oo
ooo
ooo
oo
SUMMARY OF PhD THESIS Ing. George Călin Roiban
20
The diagram presented in fig. 9, specific to the second chemical technology of weed
control (comprised by two post-emergence treatments, from which one is an precocious
one) reveals a good and very good efficacy of treatments for both moments of
determination, corresponding to first 65-75 days of vegetation period, before harvesting
showing a plus in efficacy owed to cumulating effects of the 2 treatments).
% of weed control
91,491,9
92,8
99,9
93,7
92,1 90,5
90,5591,1
92,3
98,5
92,9
91,55 90,5
78,280
82,3
88,3
84,1
81,377,6
60
70
80
90
100V1
V11
V12
V13V14
V15
V16
30 days 45 days at the harvest
Fig. 9. Weed control degree accomplished by the second technology variants in the three moments of determination (Chemical weed control: two post-emergent treatments with
associated herbicides in fractionated doses)
For the third control technology, tested in 6 variants, comprising a single precocious
post-emergence treatment with associated or complex herbicides and a late hoeing (fig. 10),
the two moments for efficacy appreciation, covering the period of maximum sensitivity of
corn crop to weeding, are practically confounded because of the control degrees which are
very close; thus, with this technology, the corn crop is saved from weed competition,
included those with belayed spring. For this technology is observed the biggest girth of the
area for control established at the end of vegetation period of corn.
LSD (p5%) = 1.44 % LSD (p1%) = 2.01 % LSD (p0.1%) = 2.84%
Ctr.
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ooo
oooooo
ooo
ooo
SUMMARY OF PhD THESIS Ing. George Călin Roiban
21
% of weed control
89,3
99,9
88,8
89,594,5
90
96,1 91,5
98,5
90,8
91,897
96,1
98,388,3
80,4
78,5
81,386,8
84,2
88
60
70
80
90
100V1
V17
V18
V19V20
V21
V22
30 days 45 days at the harvest
Fig. 10. Weed control degree accomplished by the third technology variants in the
three moments of determinations (Mixed weed control: precocious post-emergence treatment with associated or complex
herbicides followed by a mechanical weeding)
For technology IV (fig. 11), one can observe high values of control degree, registered
in the first determination, correlated to decrease of general weeding compared to control
variant, due to herbicide treatment in previous crop stubble field; during the vegetation
period of corn crop is observed a relatively constant decrease of control degree, measured
on 6 variants, some of them over passing the 3 hoeing witness at the determination moment
no 3. It is worth to mention that for this technology the level of control remains around 90%
at the determination moment no 2 (day 65-75 in the vegetation period) and over 80% at the
determination moment no 3 (before harvest) in most of the variants.
LSD (p5%) = 2.18% LSD (p1%) = 3.05 % LSD (p0.1%) = 4.31%
ooo
ooo
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o
o
Ctr.
SUMMARY OF PhD THESIS Ing. George Călin Roiban
22
% of weed control after 30 days, 45 days and at the harvest
98,5
98,8
99,9
97,698
97,8
97,5
91,4
92.5
98,5
9090,5
90
89,2
86,5
89
82,6
88,3
84,2
79,1
78,6
60
65
70
75
80
85
90
95
100V1
V23
V24
V25V26
V27
V28
Fig.11. Weed control degree accomplished by the fourth technology variants in the three moments of determinations
(Chemical weed control in two years: glyphosate-based herbicides applied pre-crop stubble and one post-emergent treatment with associated or complex herbicides)
PARTIAL RESULTS CONCERNING THE INFLUENCE OF CONTROL TECHNOLOGIES TESTED ON CORN CROP YIELD
The average crop yields registered in witness variants are 6884 kg/ha in control
variant I – classical weed control with 3 manual hoeing and only 932 kg/ha in control
variant for weeding (V2 – no hoeing).
The crop yields obtained in the variants within the chemical control technology for
corn crop with a single post-emergence treatment framed in the interval 4720 kg/ha –
variant 3 (EQUIP OD 2 l/ha + CALLISTO 0.2 l/ha) and 6320 kg/ha – variant 10 (TITUS
25DF 30 g/ha + BUCTRIL UNIVERSAL 0.8 l/ha).
-
LSD (p5%) = 3.90% LSD (p1%) = 5.47 % LSD (p0.1%) = 7.73 %
-
oo
oo
oo
Ctr.
SUMMARY OF PhD THESIS Ing. George Călin Roiban
23
The crop yield difference against control variant with 3 hoeing is statistically very
significant for most of the tested chemical control variants, except the 2 variants that used
associations of different antigraminee herbicides to antidicotyledonous herbicide BUCTRIL
UNIVERSAL 0.8 l/ha. For these variants the yield difference against the witness is under
800 kg corn grains/ha.
The crop yields obtained in the variants within the chemical control technology for
corn crop with two post-emergence treatments framed in the interval 5980 kg/ha - variant
11 (EQUIP OD 1 +1.5 l/ha + BROMOTRIL 40EC 0.6 + 0.6 l/ha) and 6385 kg/ha - variant
15 (TITUS 25DF 20 + 20 g/ha + MUSTANG 0.5 + 0.5 l/ha). Except the first variant
mentioned, in all other variants tested in this technology, the crop yields obtained overcome
6000 kg/ha, being considered better variants than those tested in the first technology. The
production yield differences against the witness variant I (3 manual hoeing) are lower then
those registered with the chemical control technology for corn crop with a single post-
emergence treatment, framing between 499 kg/ha (V15 - TITUS 25DF 20 + 20 g/ha +
MUSTANG 0.5 + 0.5 l/ha) and 904 kg/ha (V11 - EQUIP OD 1 +1.5 l/ha + BROMOTRIL
40EC 0.6 + 0.6 l/ha.
The crop yields obtained in the variants within the mixed control technology for
corn crop with a precocious post-emergence treatment with complex or associated
herbicides and a belayed mechanical hoeing, framed in the interval 6320 kg/ha - variant 18
(BASSIS 25 g/ha + Trend 0.1% and mechanical hoeing) and 6740 kg/ha - variant 22
(TITUS 25DF 30 g/ha + RING 80WG 20g/ha + Extravon 0.15l/ha and mechanical hoeing).
In all variants tested with this technology, the production yields obtained are very close to
control variant I yield, the registered differences being statistically insignificant for 3 of
them: V22 (TITUS 25DF 30 g/ha + RING 80WG 20g/ha + Extravon 0.15l/ha and
mechanical hoeing ), V20 (EQUIP OD 2 l/ha + RING 80WG 20g/ha + Extravon 0.15l/ha
and mechanical hoeing) and V17 ( TITUS PLUS 300 g/ha and mechanical hoeing); for the
other 3 variants tested, the differences are statistically significant for DL values p5% - 450
kg corn grains/ha.
It is worth to mention also for yields obtained the variants comprising associations of
anti-graminee herbicides, very efficient in Noşlac conditions, and between complex
SUMMARY OF PhD THESIS Ing. George Călin Roiban
24
herbicides and TITUS PLUS herbicide (300 g/ha). These associations, along with the
belayed mechanical hoeing, acquire a prolonged control in weeding specific to corn crop.
The crop yields obtained in the variants within the chemical control technology for
corn crop with two treatments: first one, in the previous crop stubble field with glyphosate
based herbicides and the second, post-emergence treatment (at 5-6 corn leaves) with
complex or associated herbicides, framed in the interval 6362 kg/ha - variant 28 (LEONE 36
SL 4l/ha in stubble field + BASSIS 25 g/ha + Trend 0.1%) and 6800 kg/ha - variant 24
(LEONE 36 SL 4l/ha in stubble field +TITUS 25DF 30 g/ha + Trend 0.1% + BUCTRIL
UNIVERSAL 0.8 l/ha). The production yield differences against the witness variant I are
framed between kg/ha (V24) and 384 kg/ha (V25).
By comparing all variants for weed control tested with the control variant I (3 manual
hoeing), one can observe the variants from the chemical control technology with 2
treatments: first one, in the previous crop stubble field with glyphosate based herbicides and
the second, post-emergence treatment (at 5-6 corn leaves) with associated herbicides,
followed by mixed control technology: a precocious post-emergence chemical treatment
(with associated herbicides, especially anti-graminee) and a belayed mechanical hoeing
(Table 5).
Four of the variant for weed control tested obtained a corn grains production close to
control variant I, the differences between variants or between variants and witness are
statistically insignificant. These variants are:
1) V24: LEONE 36 SL 4l/ha applied in stubble field +TITUS 25DF 30 g/ha + Trend
0.1% + BUCTRIL UNIVERSAL 0.8 l/ha applied in post-emergence;
2) V22: TITUS 25DF 30 g/ha + RING 80WG 20g/ha + Extravon 0.15l/ha + belayed
mechanical hoeing;
3) V23: LEONE 36 SL 4l/ha applied in stubble field + EQUIP OD 2l/ha + Extravon
0.15l/ha + BUCTRIL UNIVERSAL 0.8 l/ha applied in post-emergence and
4) V26: LEONE 36 SL 4l/ha applied in stubble field +TITUS 25DF 30 g/ha + Trend
0.1% + CALLISTO 0.2 l/ha. For all these variants, the average control percent,
calculated for the entire vegetation period of corn crop, surpasses 90%.
SUMMARY OF PhD THESIS Ing. George Călin Roiban
25
Table 5. Weed control efficacy and corn crops yield accomplished in all of tested variants, compared to first
control variant with 3 manual hoeing Curr.no Number
of variant Weed control variant Average
control % Significance Yield
kg/ha Significance
1 V1 Control I-3 manual hoeing 95.6 Mt 6884 Ctr. 2 V3 EQUIP OD: 2 l/ha + CALLISTO 0.2 l/ha 80.4 ooo 4720 ooo 3 V4 EQUIP OD: 2 l/ha + RING 80 WG 20
g/ha + Extravon 0,15 l/ha 84.4 ooo 5300 ooo
4 V5 EQUIP OD: 2 l/ha +LONPAR: 2l/ha 86.6 ooo 5400 ooo 5 V6 EQUIP OD: 2 l/ha + BUCTRIL
UNIVERSAL 0.8 l/ha 85.3 oo 6130 ooo
6 V7 TITUS 25DF: 30g/ha (+Trend) + CALLISTO 0.2 l/ha
81.6 ooo 5020 ooo
7 V8 TITUS 25DF: 30g/ha + RING 80 WG 20 g/ha + Extravon 0,15 l/ha
85.2 oo 5850 ooo
8 V9 TITUS 25DF: 30g/ha + LONPAR: 2 l/ha 84.3 ooo 5800 ooo 9 V10 TITUS 25DF: 30g/ha (+Trend)
+ BUCTRIL UNIVERSAL: 0.8 l/ha 85.9 oo 6230 ooo
10 V11 EQUIP OD: 1 + 1,5 l/ha + BROMOTRIL 40 EC 0,6 + 0,6 l/ha
86.7 oo 5980 ooo
11 V12 EQUIP OD: 1 + 1,5 l/ha + MUSTANG: 0,5 + 0,5 l/ha
89.1 o 6275 ooo
12 V13 EQUIP OD: 1 + 1,5 l/ha + CALLISTO 0,2 + 0,2 l/ha
86.2 oo 6260 ooo
13 V14 TITUS 25DF:20+20g/ha (Trend) +BROMOTRIL 40 EC 0,6 + 0,6 l/ha
88.3 o 6290 ooo
14 V15 TITUS 25DF: 20 + 20g/ha (Trend) + MUSTANG 0,5 + 0,5 l/ha
90.2 - 6385 oo
15 V16 TITUS 25DF: 30g/ha (+Trend) + CALLISTO 0.2 + 0.2 l/ha
87.7 o 6130 ooo
16 V17 1) TITUS PLUS: 300 g/ha 2) mechanical hoeing
87.1 oo 6520 o
17 V18 1) BASSIS: 25g/ha (Trend 0,1%) 2) mechanical hoeing
86.0 oo 6380 ooo
18 V19 1) EQUIP OD: 2,0 l/ha + BROMOTRIL 40 EC 0,8 l/ha 2) mechanical hoeing
87.5 o 6365 oo
19 V20 1) EQUIP OD: 2 l/ha + RING 80 WG 20 g/ha (+ Extravon 0,15 l/ha) 2) mechanical hoeing
92.8 - 6500 o
20 V21 1) TITUS 25DF: 20 g/ha (Trend) + BROMOTRIL 40 EC 2) mechanical hoeing
90.1 - 6400 oo
21 V22 1) TITUS 25DF: 30g/ha + RING 80 WG 20 g/ha (+ Extravon 0,15 l/ha) 2) mechanical hoeing
94.1 - 6740 -
22 V23 1) LEONE 36 SL: 4 l/ha 2)EQUIP OD: 2 l/ha +BUCTRIL U. 0.8 l
92.1 - 6730 -
23 V24 1)LEONE 36 SL: 4 l/ha 2) TITUS 25DF: 30g/ha (+Trend) +BUCTRIL UNIV: 0.8 l/ha
93.5 - 6800 -
24 V25 1)LEONE 36 SL: 4 l/ha 2)EQUIP OD: 2 l/ha +CALLISTO 0.2 l
91.1 - 6500 o
25 V26 1)LEONE 36 SL: 4 l/ha 2) TITUS 25DF: 30g/ha (+Trend) + CALLISTO 0.2 l/ha
90.1 - 6580 o
SUMMARY OF PhD THESIS Ing. George Călin Roiban
26
Curr.no Number of variant
Weed control variant Average control %
Significance Yield kg/ha
Significance
26 V27 1)LEONE 36 SL: 4 l/ha 2)TITUS PLUS: 300 g/ha
89.0 o 6420 oo
27 V28 1)LEONE 36 SL: 4 l/ha 2)BASSIS: 25g/ha (+Trend 0,1%)
88.4 o 6362 ooo
LSD (p 5%) = 6.15 % LSD (p 1%) = 8.20 % LSD (p 0.1%) = 10.68 %
LSD (p 5%) = 293 kg/ha LSD (p 1%) = 388 kg/ha LSD (p 0.1%) = 502 kg/ha
Between the control degree obtained in tested variants and the corn grains production
is established a very significant positive correlation: r = 0.859*** (fig. 12), and the linear
regression equation allows the calculation of production depending on achieved control
degree. Thus, for an average weed control of 75%, in Noşlac conditions, the production that
can be obtained is calculated with the formula y = 125.59 x – 4884.1 de 4535.15 kg/ha.
y = 125,59x - 4884,1r = 0.859***
4500
5000
5500
6000
6500
7000
78 80 82 84 86 88 90 92 94 96 98
% of weed control
yiel
d kg
/ha
Fig.12. The relationship between weed control degree (%) accomplished in tested
variants and the corn crop yield (kg/ha)
As a result of multiple comparisons with Duncan test, we can observe the following:
4 of the tested weed control variants are in the leading positions in production
classification, with differences between them (including witness variant), statistically
insignificant. These variants are: 1) V24: LEONE 36 SL 4l/ha applied in stubble field
+TITUS 25DF 30 g/ha + Trend 0.1% + BUCTRIL UNIVERSAL 0.8 l/ha applied in
post-emergence; 2) V22: TITUS 25DF 30 g/ha + RING 80WG 20g/ha + Extravon
0.15l/ha + belayed mechanical hoeing; 3) V23: LEONE 36 SL 4l/ha applied in stubble
field + EQUIP OD 2l/ha + Extravon 0.15l/ha + BUCTRIL UNIVERSAL 0.8 l/ha
applied in post-emergence and 4) V26: LEONE 36 SL 4l/ha applied in stubble field
SUMMARY OF PhD THESIS Ing. George Călin Roiban
27
+TITUS 25DF 30 g/ha + Trend 0.1% + CALLISTO 0.2 l/ha. Three of these variants
pertain to weed control technology no IV, the success being granted by the culture
hygiene achieved with herbicide LEONE 36 SL – 4l/ha applied in previous triticale
stubble field and by the efficacy of combinations of herbicides applied post-emergence
in the corn crop (especially BUCTRIL UNIVERSAL 0.8 l/ha applied in association with
TITUS 25DF 30 g/ha + Trend 0.1% or EQUIP OD 2l/ha + Extravon 0.15l/ha or the
combination between 2 graminicide herbicides: TITUS 25DF: 30g/ha + RING 80 WG
20 g/ha + Extravon 0,15 l/ha completed with a belayed mechanical hoeing.
3 variants: V20: EQUIP OD: 2 l/ha + RING 80 WG 20 g/ha (+ Extravon 0,15 l/ha) +
mechanical hoeing; V17: TITUS PLUS: 300 g/ha + mechanical hoeing and V25: LEONE
36 SL: 4 l/ha + EQUIP OD: 2 l/ha +CALLISTO 0.2 l, are near the leading variants by
means of the obtained crop production, but statistically are significant different only
from the witness variant I – 3 manual hoeing.
Another 3 tested variants for weed control: V27: LEONE 36 SL: 4 l/ha + TITUS PLUS
300g/ha; V21: TITUS 25DF: 30g/ha + Trend 0.1% + BROMOTRIL 40EC 0.8 l/ha +
mechanical hoeing and V19: EQUIP OD: 2 l/ha + BROMOTRIL 40EC 0.8 l/ha +
mechanical hoeing, obtained crop productions very close to those mentioned above
0
10
20
30
40
50
60
70
V1
V2
4
V2
2
V2
3
V2
6
V2
0
V1
7
V2
5
V2
7
V2
1
V1
9
V1
5
V2
8
V1
8
V1
4
V1
2
V1
3
V1
0
V6
V1
6
V1
1
V9
V8
V5
V4
V7
V3
V2
q/ha yield
Fig. 13. Variants of weed control classification depending on corn crop yield
SUMMARY OF PhD THESIS Ing. George Călin Roiban
28
PARTIAL RESULTS CONCERNING THE ECONOMIC EFFICIENCY OF IMPROVED TECHNOLOGIES FOR POST-EMERGENCE WEED CONTROL IN
CORN CROP
In the general classification of profit obtained from all 28 tested variants, the variant
22, component of weed control technology no III, occupied the first place; in this variant
were tested 2 anti-grass herbicides associated (TITUS25DF 20 g/ha and RING 80WG 20
g/ha), followed by a belayed mechanical hoeing.
For the first 13 variants in the classification, the average weed control is framed
between 85.3% (V14) and 94.1% (V22), the crop production obtained is framed between
6290 kg/ha (V14) and 6800 kg/ha (V24), and the profit between 1367.96lei/ha (V26) and
1589.59 lei/ha (V22). From all 26 variants tested (2 being control variants), the profit
obtained is under 1000 lei/ha only for 4 variants, all in the first tested technology (chemical
– a single post-emergence treatment). In these variants, the average percent of control
frames between 80.4 (V3) and 86.6 (V5), and the registered crop yields are all under 6000 de
kg/ha.
In the first 13 variants in the classification we can find all 6 variants from the mixed
weed control technology (single precocious post-emergence treatment – at 2-3 corn leaves,
followed by a belayed mechanical hoeing), 4 variants from the 2 years chemical technology
(glyphosate treatment in the previous crop stubble field and a post-emergence treatment in
corn crop with associated or complex herbicides), 2 variants from the chemical control
technology with 2 post-emergence treatments with fractioned doses herbicides
(combinations between TITUS 25DF 20+20 g/ha and MUSTANG 0.5+0.5 l/ha or
BROMOTRIL 40EC 0.6+0.6 l/ha) and a variant from chemical technology with a single
post-emergent treatment at 5-6 corn leaves stage (variant 10 association of TITUS25DF 30
g/ha and BUCTRIL UNIVERSAL 0.8 l/ha).
SUMMARY OF PhD THESIS Ing. George Călin Roiban
29
Table 6.
Variants classification depending on accomplished total profit Classification
Number of variant
Weed control variant Average weed control %
Yield kg/ha
Total Profit lei/ha
Segnificance
1 V22 1) TITUS 25DF: 20g/ha + RING 80 WG 20 g/ha (+ Extravon 0,15 l/ha) 2) mechanical hoeing
94.1 6740 1589.59 A
2 V24 1)LEONE 36 SL: 4 l/ha 2) TITUS 25DF: 30g/ha (+Trend 0.1%)
+BUCTRIL UNIV: 0.8 l/ha
93.5 6800 1575.81 A
3 V17 1) TITUS PLUS: 300 g/ha(Trend 0,1%) 2) mechanical hoeing
87.1 6550 1521.59 AB
4 V21 1) TITUS 25DF: 20 g/ha (Trend 0,1%) + BROMOTRIL 40 EC 0.8 l/ha 2) mechanical hoeing
90.1 6400 1515.79 AB
5 V10 TITUS 25DF: 30g/ha (+Trend 0,1%) + BUCTRIL UNIVERSAL: 0.8 l/ha
85.9 6230 1487.85 AB
6 V20 1) EQUIP OD: 2 l/ha + RING 80 WG 20 g/ha (+ Extravon 0,15 l/ha) 2) mechanical hoeing
92.8 6500 1476.59 ABC
7 V18 1) BASSIS: 25g/ha (Trend 0,1%) 2) mechanical hoeing
86.0 6320 1468.84 ABC
8 V23 1) LEONE 36 SL: 4 l/ha 2)EQUIP OD: 2 l/ha +BUCTRIL U. 0.8 l + Extravon 0,15 l/ha
92.1 6730 1457.56 ABCD
9 V15 TITUS 25DF: 20 + 20g/ha (Trend 0,1%) + MUSTANG 0,5 + 0,5 l/ha
90.2 6385 1409.46 ABCD
10
V19 1) EQUIP OD: 2,0 l/ha +Extravon 0,15 l/ha+ BROMOTRIL 40 EC 0,8 l/ha
2) mechanical hoeing
87.5 6365 1396.79 ABCD
11 V28 1)LEONE 36 SL: 4 l/ha 2)BASSIS: 25g/ha (+Trend 0,1%)
88.4 6362 1384.21 ABCDE
12 V14 TITUS 25DF:20+20g/ha (Trend0,1%) +BROMOTRIL 40 EC 0,6 + 0,6 l/ha
88.3 6290 1373.64 ABCDE
13 V26 1)LEONE 36 SL: 4 l/ha 2) TITUS 25DF: 30g/ha (+Trend0,1%)
+ CALLISTO 0.2 l/ha
90.1 6580 1367.96 ABCDE
14 V27 1)LEONE 36 SL: 4 l/ha 2)TITUS PLUS: 300 g/ha (+Trend0,1%
89.0 6420 1350.83 BCDE
15 V6 EQUIP OD: 2 l/ha + BUCTRIL UNIVERSAL 0.8 l/ha +Extravon 0,15 l/ha
85.3 6130 1309.85 BCDEF
16 V12 EQUIP OD: 1 + 1,5 l/ha + Extravon 0,15 l/ha + MUSTANG: 0,5 + 0,5 l/ha
89.1 6275 1259.46 CDEFG
17 V8 TITUS 25DF: 30g/ha + RING 80 WG 20 g/ha + Extravon 0,15 l/ha
85.2 5850 1256.25 CDEFG
18 V25 1)LEONE 36 SL: 4 l/ha 2)EQUIP OD: 2 l/ha +CALLISTO 0.2 l
91.1 6500 1244.96 DEFG
19 V9 TITUS 25DF: 30g/ha (+Trend 0,1%) + LONPAR: 2 l/ha
84.3 5800 1171.18 EFG
20 V11 EQUIP OD: 1 + 1,5 l/ha + BROMOTRIL 40 EC 0,6 + 0,6 l/ha
86.7 5980 1123.76 FG
21 V16 TITUS 25DF: 30g/ha (+Trend0,1%) + CALLISTO 0.2 + 0.2 l/ha
87.7 6130 1075.58 GH
22 V13 EQUIP OD: 1 + 1,5 l/ha + CALLISTO 0,2 + 0,2 l/ha
86.2 6260 1045.96 GH
23 V4 EQUIP OD: 2 l/ha + RING 80 WG 20 g/ha + Extravon 0,15 l/ha
84.4 5300 898.25 HI
SUMMARY OF PhD THESIS Ing. George Călin Roiban
30
Classification
Number of variant
Weed control variant Average weed control %
Yield kg/ha
Total Profit lei/ha
Segnificance
24 V5 EQUIP OD: 2 l/ha +LONPAR: 2l/ha + Extravon 0,15 l/ha
86.6 5400 888.05 HI
25 V7 TITUS 25DF: 30g/ha (+Trend 0,1%) + CALLISTO 0.2 l/ha
81.6 5020 718.25 I
26 V3 EQUIP OD: 2 l/ha + CALLISTO 0.2 l/ha + Extravon 0,15 l/ha
80.4 4720 435.25 J
27 V1 Control I-3 manual hoeing 95.6 6884 166.22 K28 V2 Controls II – no hoeing 0.00 932 0.00 K
SD Values lei/ha: 186.18 196.1 175.45 ...................... 230.83 231.04 231.25
RECOMMENDATIONS FOR TECHNOLOGIES AND VARIANTS FOR WEED CONTROL IN CORN CROP, TECHNOLOGICALLY, ECOLOGICALLY AND
ECONOMICALLY EFFICIENT
Taking into account that in the experimental field the annual monocotyledonous
weed species are in majority, is very important the rigorous control of those species in the
first part of corn crop vegetation, and the belayed hoeing only completes the efficacy of
weed control of perennial and annual dicotyledonous species which are not affected by
herbicides.
The late infestations are much better controlled by hoeing, compared to fractioned
herbicide treatments, applied in periods previous to hoeing. If the second moment for weed
control (chemical or mechanical) in the vegetation period of corn crop is belayed, the
weeding is much lower in the second part of vegetation period. Because the moment of
herbicides application is limited by the vegetative phase of corn (maximum 6 leaves), the
second chemical treatment cannot be pushed further in time, while the hoeing can be carried
out later.
The average rate of profit classifies the tested weed control technologies as follows:
Technology no III (mixed control technology for corn crop with a precocious
post-emergence treatment and a belayed mechanical hoeing), with an average
rate of profit of 86.45%;
Technology no IV (2 years chemical weed control with a total action herbicide
treatment in the previous crop stubble field and a post-emergence treatment in
corn crop), with an average rate of profit of 74.3%;
Technology no II (chemical control technology for corn crop with two post-
emergence treatments), with an average rate of profit of 64.72%
SUMMARY OF PhD THESIS Ing. George Călin Roiban
31
Technology no I (chemical control technology for corn crop with a single post-
emergence treatments), with an average rate of profit of 51.97%.
Table 7.
Comparative analysis of weed control technologies depending of the rate of profit
rate of profit %)% Classification
Weed control technologies classification 1 2 3 4 5 6 7 8 Average Signific.
1. Mixed: precocious post-emergent treatment with associated or complex herbicides followed by a mechanical weeding
V17
86.8
V18
86.9
V19
77.5
V20
82.1
V21
90.8
V22
94,6
- - 86.45
A
2. Chemical in 2 years: glyphosate-based herbicides applied pre-crop stubble and one post-emergent treatment with associated or complex herbicides
V23
76.4
V24
86.4
V25
62.1
V26
71.2
V27
72.7
V28
77.0
- - 73.3
AB
3. Chemical: 2 post-emergent treatments with associated herbicides in fractionated doses
V11
60.2
V12
67.1
V13
50.2
V14
77.6
V15
79.1
V16
54.1
- - 64.72
BC
4. Chemical: single post-emergent treatment with associated herbicides
V3
22.6
V4
51.3
V5
49.0
V6
74.6
V7
39.0
V8
75.3
V9
67.7
V10
89
51,97
C
5. Mixed: precocious post-emergent treatment with associated or complex herbicides followed by a mechanical weeding
5.1 D
SD Values ( %) 13.5 14.19 14.6 14.92
The variants recommended for corn crop farmers from Noşlac area are, tided up from
profit point of view:
• V22: TITUS 25DF 30g/ha + RING 80WG 20g/ha +Trend 0.1% + belayed mechanical
hoeing, with a total profit of 1589.59 lei/ha;
• V24: LEONE 36SL 4l/ha in previous crop stubble field + TITUS 25DF 30g/ha +Trend
0.1% + BUCTRIL UNIVERSAL 0.8 l/ha – post-emergence, with a total profit of
1575.56 lei/ha;
• V17: TITUS PLUS 300g/ha + Extravon 0.15 l/ha + belayed mechanical hoeing, with a
total profit of 1521.59 lei/ha,
SUMMARY OF PhD THESIS Ing. George Călin Roiban
32
• V21: TITUS 25DF 30g/ha + Trend 0.1% BROMOTRIL 40EC 0.8 l/ha + belayed
mechanical hoeing, with a total profit of 1515.79lei/ha,
• V10: TITUS 25DF – 30g/ha + Trend 0.1% + BUCTRIL UNIVERSAL – 0.8 l/ha, with a
total profit of 1487.85 lei/ha;
• V20: EQUIP OD – 2l/ha + RING 80WG 20g/ha +Extravon 0.15l/ha + belayed
mechanical hoeing, with a total profit of 1476.59 lei/ha, and
• V18: BASSIS 25g/ha + Trend 0.1% + belayed mechanical hoeing, with a total profit of
1468.84 lei/ha
• V23: LEONE 36SL 4l/ha in previous crop stubble field + EQUIP OD – 2l/ha + Extravon
0.15 l/ha + BUCTRIL UNIVERSAL 0.8 l/ha – post-emergence, with a total profit of
1457.56lei/ha,
• V15: TITUS 25DF 20+20g/ha + Trend 0.1% + MUSTANG 0.5+0.5 l/ha with a total
profit of 1409.46 lei/ha;
• V19: EQUIP OD 2l/ha + Extravon 0.15l/ha + BROMOTRIL 40EC 0.8 l/ha + belayed
mechanical hoeing, with a total profit of 1396.79lei/ha,
• V28: LEONE 36SL 4l/ha in previous crop stubble field +BASSIS 25g/ha + Trend 0.1%
post-emergence, with a total profit of 1384.21 lei/ha,
• V14: TITUS 25DF 20+20g/ha + Trend 0.1% BROMOTRIL 40EC 0.6+0.6 l/ha with a
total profit of 1373.76lei/ha and
• V26: LEONE 36SL 4l/ha in previous crop stubble field + TITUS 25DF 30g/ha +Trend
0.1% + CALLISTO 0.2l/ha – post-emergence, with a total profit of 1367.96 lei/ha.
The results included in the thesis confirm the opportunity for applying the weed
control method in post-emergence in corn crops cultivated in high plane areas from Alba
County.
The positive impact of some variants or weed control technologies on weeding
characteristics, corn crop development, grains production and profit is a very good motif to
recommend these variants to corn crop farmers from Alba County and elsewhere.
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