E.6. Penyakit abiotik

Penyakit abiotik (kondisi cuaca)

Penyakit abiotik (kekurangan unsur hara)

ENVIRONMENTALFACTORS THAT CAUSE

PLANT DISEASES

Temperature, moisture, oxygen, light, airpollution, nutricial deficiencies in plants,soil mineral toxic to plant, herbicideinjury, hail injury, lighting, otherimproper agricultural practices

GENERAL CHARACTERISTICS• Non infectious diseases of plants, is that are

caused by the lack or excess of something thatsupports life

• Non infectious diseases occur in the absence ofpathogens and cannot, therefore, be transmittedfrom diseased plant to healthy plants

• Non infectious diseases may affect plant in allstages of their lives (e.g., seed, seedling, matureplant, or fruit), and they may cause damage inthe field, in storage, or at the market

• The symptoms caused by non infectiousdiseases vary in kind and severity

• Symptoms may range from slight to severe, andaffected plants may even die

DIAGNOSIS• Sometimes made easy by the presence of

characteristic symptoms• Carefully examining and analyzing several

factors: the weather conditions prevailing beforeand during the symptoms; recent changes in theatmospheric and soil contaminants; and thecultural practices

• Often, the symptoms are closely resemble thosecaused by pathogens

• By growing plants under conditions in which thedegree of suspected environmental factors hasbeen adjusted to normal

CONTROL

Non infectious diseases can be controlledby ensuring that plants are not exposed tothe extreme environmental conditionsresponsible for such diseases or bysupplying the plants with protection orsubstances that would bring theseconditions to level favorable for plantgrowth

Penyakit abiotik(kondisi cuaca)

A. HIGH-TEMPERATURE EFFECT

• Seems to cause its effects on the plant inconjunction with the effects of otherenvironmental factors, particularly excessivelight, drought, lack of oxygen, or high windsaccompanied by low relative humidity

• Sunscald injury, appearing on the sun-exposedsides of fleshy fruits and vegetables, such aspeppers, apples, tomatoes, onion bulbs, andpotato tubers

• Kill young seedlings, causes cankers at thecrown on the stem of older plants

• Strawberry, tomato and pepper with fruitlesions due to sunburn/sunscald

• Water melon fruit lesions due to sunburn/sunscald

• Sunscald and growth of secondary organisms

B. LOW-TEMPERATURE EFFECT• Far greater damage to crops is caused by low

than high temperatures• Excessive sweetening and on frying, undesirable

caramelization of potatoes• late frosts to young leaves and meristematic

tips• The frost killing of buds of peach, cherry, and

the killing of flowers, young fruit, and sometimessucculent twigs of most trees

• Kill the young roots of trees or cause barksplitting and cancer development

• Discolored corky tissue on surface of apple orpear fruit

• frost

• Foliar burn from late frost tosycamore plantation

• Tissue burned by late frost

C. LOW SOIL MOISTUREEFFECTS

• Moisture disturbances in the soil areprobably for more plants growing poorlyand being unproductive annually, overlarge areas than any other singleenvironmental factor

• Plants usually remain stunted, are palegreen to light yellow, have few, small anddrooping leaves, and wilt and die

• Plants are also more susceptible tocertain pathogens and insects

• Water stress in the rice paddy. The lack of waterin the soil reduces the ability of the plant toextract essential nutrients from the soil

• Corn with rolled leaves, indicative of waterstress.

• Close-up of drought stress onmagnolia (Magnolia)

D. HIGH SOIL MOISTUREEFFECTS

• Excessive soil moisture occurs much lessoften than drought, may result in moreserious and quicker damage or death

• Plants have lack vigor, wilt frequently,leaves are pale green or yellowish green,and plant die

• Edema or oedema (swelling)

• This creeping juniper (Juniperus) diedfrom overwatering

• Flooded soybean field,

• Flooding effect on plant

E. INADEQUATE OXYGEN• Lack oxygen may cause desiccation of

roots of different kind of plants inwaterlogged soil

• A combination with high air temperaturecauses root collapse in plants

• Blackheart of potato

F. LIGHT• Lack of sufficient light retards chlorophyll

formation and promote slender growthwith long internodes, thus leading to palegreen leaves, spindly growth, andpremature drop of leaves and flowers(etiolation)

• Etiolated plants are usually thin and talland are susceptible to lodging

• Etiolated - light beans

• Etiolated seedling

G. AIR POLLUTAN• Ozone• Acid rain

• Bronzing on leaves caused by ozone

• Ozone damage to white pine (Pinus strobus)

• Browning needles on white pine (Pinus strobus)caused by air pollution