COTT301 Cotton Crop Protection

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27-07-2021

Questions:

Q1) On a product label, under the application heading it asks for a spray volume of 80 L/Ha or less, Aim for 250?300 micron droplets.

What spray quality does this correspond to?
Assuming my average spraying speed was 16 kph, and preferred operating pressure range was 3?4 bar, give an example of a nozzle that would meet this labels requirements.

Q2) Some product labels specify that a coarse spray or larger quality must be used.

If I had to apply such a product and the spray rig I wanted to use was limited to a maximum pressure of 3 to 3.5 bar, what kind of nozzle do you think I should select?

Q3) Assume you wanted to spray a paddock at 70 L/Ha, traveling at 18 km/h and needed to produce a medium spray quality.

What nozzle (size and type) would you recommend, if the machines pump and plumbing had a maximum capacity of 6 bar?
With the nozzle you selected in a) suggest a suitable minimum operating pressure and speed that corresponds to at 70L/Ha.
If the product being applied required the addition of an oil based adjuvant, would that change the nozzle you may recommend for this job? (Explain why/ why not).

Q4) A grower needs to do a spray job that required of a tank mix of Glyphosate and Surpass (label recommends a minimum of 50L/Ha for tank mixes and a coarse – very coarse spray quality). They have asked you to help them select a nozzle to be purchased for this type of job.

Before selecting a nozzle, what questions would you need to ask the grower?

Q5) According to the APVMA What is a no spray zone ?

Q6) Explain the role of width in the formula L/Ha = L/min/nozzle x 600 / speed / width Give 3 examples of how the term ‘ width’ may be applied in different application scenarios (they must all be related to application in a cotton situation).

Q7) How does an automatic rate controller maintain a constant application rate as the machine varies its speed

Q8) Suggest the minimum pressures that you would recommend the following nozzles be run at:

pre?orifice (not air inducted) such a Hardi LD
a low pressure air inductions such as a hardi minidrift or agrotop airmix
ca high pressure air induction such as a Teejet AI or an Agroptop Turbodrop

Q9) A standard flat fan producing a fine spray quality will have 40% or more of its volume in droplet sizes that are susceptible to evaporation and drift. How much do you reduce that driftable fraction as you move to coarser spray qualities ?

Q10) If you had an area of 100 Ha to treat for weeds and the product selected for this task had to be applied at 1.5 L/Ha of chemical in a total application volume of 50L /Ha, using a 1200L tank: Complete the following calculations and show your working out.

How much chemical in total would I need to complete this job?
What would be the total water volume required for this job?
How many Ha would one tank load of 1200L treat ?
How much chemical would need to be added per 1200L tank load ?
How many Tank loads would be need for this job ?
If the last tank load is less than 1200L, what total volume (water) would it be and how much chemical would you need to add for that load ?

Q11) List at least 6 factors (equipment or decision) that will reduce the potential for spray drift to occur when using a ground rig.

Answers:

Solution 1

BCPC Fine Quality
QS 80 -025 (60 M)

Solution 2

Nozzle type will be TT11004

Solution 3

TT11003
Pressure = 4.41 bar, and speed is 16 km /h
We have to use one mark finer nozzle, in this case TT11003 of 5 is enough, this is due to the reason that droplet size increases after addition of oil based adjuvant.

Solution 4

Carefully read the label, Ask for operating condition, Calculate required nozzle discharge and See carefully corresponding nozzle catalogue. In this condition one of the possible nozzle should be QS 80 -015 (80 M)

Solution 5

According to Australian pesticide and veterinary Medicine authority is power by act from the Australian government that, the area where there is chances of wind blow from crop area to urban area during application of pesticides, these area can get poisonous effect due to use of pesticides, therefore, these area are restricted for pesticide or termed as No-spay zone. There is a mandatory rule for grower to use only those pesticides which is allowed in that particular zone.

Solution 6

In the given formula, width stands for nozzle spacing, the role of nozzle in particular this formula is to categorize the output of nozzle, for different type of crops and different size of nozzle spacing is also recommended for best performance.

For cotton situation, for 50 cm nozzle spacing, applicable L/Ha is 18.7, 28.0, 37.3 for nozzle size 11001, 110015, 11002 respectively is used for 18 km/h speed

Similarly for same spacing, and speed 24 km/h L/ha is 14 , 21, 28 for same type of nozzle

Solution 7

There is several possible technologies for automatic rate controller, most of them are electronically closed loop system, In some system, sensors are given in front side, it detects the speed of vehicle and adjust the spray accordingly, Green Star is working on this kind of technology. Some is directly connected with speedometer which adjust rate of flow as per speed of sprayer in the field.

Solution 8

The minimum pressure for Pre orifice, Hardi LD, and no air induced is 20 psi for target is 40
For Low pressure air inductions such as hardi minidrift or 30 psi for target 40
For high pressure air induction such as Teejet or an Agrotop Turbodrop = 40 psi at 70 target

Solution 9

The drupelets which is less than 100 microns, evaporates rapidly, the given droplet size which evaporates around 40% is about 120 microns, to enables 100 % , we have to increase droplet size about 150 microns this will withstand for some time.