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Troubleshooting Aerial Application of Forestry

Herbicides

AAFMP AGM Technical Session

October 11, 2018

Milo Mihajlovich, RPF 076

Introduction

• Aerial application is a highly technical aspect of silviculture that involves many moving parts AND

• We use aerial application of herbicides to manage/nudge biological systems

• Stacking complexity on complexity can yield “interesting” results

• I will talk today about how silviculturists can use application and biological “tools” to diagnose causes of “interesting” results and thereby avoid re-occurrence

2017-10-11 Milo Mihajlovich, RPF 2

Introduction

• I will identify a number of “interesting” results, then• Discuss how I set about diagnosing cause

• Describe how I verified my diagnosis

• Outline solutions or preventative methods to prevent reoccurrence

• Distill this to a diagnostic tool or method

• Emphasis should be on the methods and approach as I am identifying and illustrating the tools silviculturists can use to problem solve

• First off, though, I will outline some key principles about forestry aerial application that underpin the diagnostic approach I use


Basic Principles

1. Don’t blame the herbicide!• Failed treatments are frequently “blamed” on something being wrong with

the herbicide.

• This is extremely unlikely as herbicide manufacturers in North America work to tolerances of between 1 and 5% i.e. if a formulated herbicide contains more (or less) than 1 – 5% of the guaranteed rate of active ingredient the product is not packaged for sale – it is reformulated to meet specification.

• Therefore I generally look for causes other than herbicide quality when I find “interesting” results.


Basic Principles

2. Blame the herbicide!• Newer proprietary formulations of glyphosate contain more effective

surfactants and are generally more aggressive salts than the older isopropyl amine salts with ethoxylated tallow amine surfactants

• These formulations are much more effective at penetrating plant cuticle than the older formulations

• Conifer tolerance to glyphosate is conferred by the tree having sufficient cuticular wax to avoid uptake of glyphosate

• Therefore more aggressive herbicides require that we ensure trees have a fully developed wax layer before we apply said herbicides

• “Interesting” results seem to be more common pine – we will talk more about this later


Basic Principles

3. Accu – Flow™ nozzles provide superior placement of herbicides at a price –• ACCU – FLOW nozzles are vaguely

“V” shaped - causing a “V” shaped (trapezoidal) pattern


Basic Principles

3. Accu – Flow™ nozzles provide superior placement of herbicides at a price –• The net result is a trapezoidal

pattern

• Thus pattern width varies with nozzle to target distance…

A/C Type 10 20 30

Astar BA/B3 16 19

Astar BA/B3 16 19

Hughes 500D 9 11

Nozzle to Target (m)

TABLE 1. SWATH WIDTH by RELEASE

HEIGHT AF 0.016 X 74 nozzles

I.e. 10-m change in nozzle to target = 20% change in swath AND CALIBRATION!


Basic Principles

4. Helicopters spray in rectangles much like painting with a brush• Thus if one finds lines or

rectangles in application related problems the problem is likely related to application technology or technique in some…


Basic Principles

5. Guidance GPS records are powerful tools…• Provide a clear spatial record of where the spray boom was turned on – not

necessarily where the spray cloud landed.

• Unlocking the shapefile breadcrumbs provides a wealth of information, including• Speed during application

• Altitude during application

• Exact time and date during application


Basic Principles

5. There is a wonderful array of weather and climatic data available to use in diagnosis

• Fire lookout tower weather – temperature, RH, wind speed, wind direction, Fire Weather and Fuel Status indices e.g. drought code

• Environment Canada meteorological weather downloadable free from:

• http://climate.weather.gc.ca/historical_data/search_historic_data_e.html


Basic Principles

6. The fundamental biology of conifer release is:• Conifer is adequately cutinized to avoid herbicide injury

• Competitive vegetation is still biologically active and hence susceptible to the herbicide• I.e. woody vegetation has greater than 30 – 40% green foliage, herbaceous vegetation has

greater than 50% green foliage and

• There has been less than 7° of accumulated frost

• The foregoing criteria are site specific

White spruce with glyphosate injury:Stunted, achlorotic buds on new growthShort lateral and terminal leader growth


Case Study One

A cutblock GPS mapped at 171 ha is reported by the contractor has having been fully treated (i.e. 171 ha). The following spring there are substantial portions of the block showing no herbicide symptoms while treated portions show a high degree of control. The silviculturist needs to determine how much herbicide was used and where it was applied…


Case Study One

This a very simple GIS exercise using the guidance GPS treatment record file. Simply assign the spray lines in the file the nominal swath width of the spray aircraft. Then untwine the spray lines and determine the area of each (i.e. length X swath width). Total these areas and one has the treated area.

In this example a total of 171 ha had, indeed, been treated. However, some portions of the block had been sprayed multiple (2 or 3) times while the portions showing no control had not been sprayed.

Cause – pilot did not pay adequate attention to swath placement and coverage


Case Study Two

The silviculturist hired a new spray contractor who had previously applied insecticides and fungicides in an agricultural setting using disk-core nozzles. The contractor installed Accu-Flow™ 0.028 X 32 nozzles as requested, and calibrated to apply 50 L/ha of spray solution.

The contractor then treated approximately 150 ha of chemical site preparation in white pine shelterwood (i.e. spraying from 40-m above target vegetation). The contractor applied 4 L/ha of VisionMax.

On assessing the sprayed area the silviculturist found lines in the sprayed area had bands of treatment effectiveness – narrow bands of partially controlled vegetation and wider bands very dead vegetation.


Case Study Two

On being asked to provide a diagnosis I called the contractor and asked him to describe his calibration procedure. It was entirely adequate with one substantial exception…

He calibrated from 12-m above ground and achieved a 16-m swath. Based on my rule of 20% swath width increase for each 10-m increase in nozzle to target distance his likely achieved swath width was 22-m.

Thus when he thought he was treating one ha he was actually treating 1.38 ha of actual area.


Case Study Two

• The likely actual pattern of application.


Case Study Two

• The likely achieved outcome of application.

Zone of reduced treatment effectiveness

Zone of greater than expected treatment effectiveness.

Solution – calibrate ACCU-FLOW nozzles at theexpected height of application!


Case Study Three

• A silviculturist applying glyphosate for conifer release to blocks largely clearcut but with retained structure on the blocks for habitat purposes; using ACCU-FLOW 0.016 x 74 nozzles to apply 30 L/ha from a calibration height of 20 m above ground.

• The retained structure was primarily eastern white pine. The terrain the blocks were located on was quite hilly.

• The silviculturist was seeing a high degree of variability in outcomes with some areas showing marginal efficacy while other areas were showing considerable crop injury on jack pine.


Case Study Three


Case Study Three

• My diagnosis was that variations in application height were causing substantial variation in swath width – see Case Study Two – and that this variability was resulting in substantial variation in herbicide rate between and across cutblocks.

• My further contention was that the substantial nozzle to target distance occasioned by eastern white pine meant that a considerable portion of the spray solution was evaporating and entraining prior to reaching the target vegetation.

• The silviculturist strongly disputed my diagnosis.


Case Study Three

• I asked the silviculturist to open his Ag-Nav record files in ARC View and to tell me the height above mean sea level of the swath in an area with very little efficacy and then in an area with jack pine injury.

• In the former height above MSL was 852-m, in the latter 830-m.

• I used my handheld GPS with barometric altimeter to determine ground surface height was 814-m above MSL.

• So nozzle to target distance ranged from 38 m to 12 m. (See Case Study Two)


Case Study Three

• The silviculturist worked with his GIS analyst to drape the altitude data from the treatment shape files over his FMA bare ground digital elevation model data and came up with a categorical assessment of nozzle to target distance that showed most openings were sprayed at 30-35 m or 35-40 m nozzle to target distance and that all blocks showing jack pine injury were sprayed at less than 15 m above ground.

• The solution – calibrate at 35 m above ground and maintain that height regardless of the presence of retained structure (eastern white pine) on the block.


Case Study Four

• I had worked for the same forest company for 5 years assessing blocks, prescribing treatments, planning and implementing aerial spray programs. With generally very good efficacy.

• Doing the Off-Target Application checks on the 5th year’s spray program efficacy was very poor. There was minimal control of grass and control of aspen was very spotty both across and between blocks.

• We expanded the assessment to encompass all sprayed blocks and found the same results across the entire program.

• We then discussed this with adjacent FMA holder who found similar outcomes on their program.


Case Study Four

• We assessed treated blocks in more detail and began to see a pattern where efficacy on aspen was poorer on wet or low sites than on upland or dryer sites – on both programs. Likewise efficacy on reedgrass (a moist to wet site species) was fair to poor across both programs.

• Downloading the Environment Canada climate data for the previous growing season (May through end of July) showed that precipitation in the area with poor efficacy was more than twice normal (i.e. 51 cm instead of the normal 23 cm). This led us to believe the failure was due to the wet season slowing the metabolic activity of target vegetation to the point where herbicide uptake and translocation were impaired.


Case Study Four

• We shared photographs of the poor efficacy, results of our assessments and our analysis with Monsanto (manufacturer of the herbicide). They concurred and honored their product replacement guarantee – replacing all the herbicide used that year.


Case Study Five

• A customer and I planned a conifer release treatment of several very old plantations arising from the “Maintaining our Forests” (MoF) program.

• The blocks were fully stocked with sapling white spruce and with almost pole sized aspen heavily infected with a variety of diseases (notably Hypoxylon and Fomes cankers)• The cankers were likely a result of failed brush mowing treatments made in

the late 1980’s


Case Study Five• Our initial plan was treat the area

with Release™ herbicide using disk-core nozzles applying 50 L/ha of solution • This would allow us to treat in late

June and thus not make conifer release season even more busy

• Release is a coverage driven product so we needed the small droplet size provided by disk-core nozzles

• When my customer saw the pattern associated with disk-core nozzles they insisted that we switch the treatment to Vision using AccuFlow nozzles


Case Study Five

• After our initial treatments using Release and prior to final treatments with Vision a forest tent caterpillar outbreak defoliated a substantial portion of two the blocks we planned to treat with Vision• We noticed this when flying the area to assess effectiveness of the Release

treatment

• We considered dropping the defoliated blocks but decided instead to see if they recovered from defoliation prior to our planned treatment.


Case Study Five

• We re-assessed the forest tent caterpillar affected blocks at the start of conifer release season and decided that they had recovered at least 50-75% of the foliage lost during the outbreak

• We proceeded to spray these blocks as part of completing treatment of the MoF project area

• And the result….


Case Study Five

MoF block that was not affected by forest tent caterpillar outbreak.

MoF block that was defoliated and re-foliated prior to treatment


The learning from this exercise was that even species highly susceptible to glyphosate need to be physiologically active to be adequately controlled.

Conclusions


• As with any intervention in biological systems, successful use herbicides depends on:

1. Understanding and adhering to the basic biology that underpins conifer release treatments

2. Understanding the strengths and limitations of the application system

3. Understanding the efficacy and tolerance bounds of the particular herbicide used

• We have tremendously powerful diagnostic tools in1. Our understanding of how herbicides work in the plant

2. The record of treatment provided by GPS guidance systems

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