When pesticide producers come out with a product, part of the process is developing a “label rate” to inform the operator at what level of concentration the product will be effective. These chemists spend enormous resources working with regulators and conducting field trials to come up with a recommended application rate that they feel will best fit your plantation, but how can they really consider all the factors? If you spray strictly by the label rate, here are some considerations you should think about that may cause over or under application;

Plant Stage of Growth: – Yearly/Seasonal Cycle
As plants transition through winter, spring, summer and fall they go dormant, with no foliage at all, to sprouting new shoots, to a full and thick canopy, and then shedding their leaves and starting again. Grapes have their entire canopy removed over winter and start the spring with almost nothing! The leaves and foliage of a plant present exponentially more surface area to cover, and constantly change, while the label rate does not.

Plant Stage of Growth: -Life Cycle
When you first start your farm the plants are mere sticks in the ground, destined to mature over many years into a full old plantation. Every year presents its own challenges in terms of how much yearly/seasonal growth that plant is going to produce and the susceptibility of that plant to certain pests as it ages.

Row Spacing:
Your pesticide producer has no idea if you’ve planted your farm with 10ft row spacing or 5ft row spacing. For you it could mean double the amount of plants to spray in the same acre as your neighbor!

Trellis/Canopy type:
A conventional freestanding apple plantation might have 200 trees in one acre, while a super spindle apple plantation could have 900! A single cordon VSP trellis in grapes could produce half the foliage of a Lyre or Geneva Double Curtain trellis.

Verity:
Often depending on verity we can see major variations in both the amount of growth and foliage, and the susceptibility to different disease’s

Pressure/Environmental Factors:
Is your site on the wet and humid coast, or the dry and arid interior? Maybe your neighbor has planted a crop that has promoted or hindered the development of a certain pest at your farm. There are lots of extenuating factors that might affect your spray program.

Is a one-size-fits-all label rate the best approach to spraying when we have all this variability? And how should we adapt all this information into useful inputs that we can use to improve our spraying efficacy? Here is where things get tricky, if we are going to go off the producers recommended rates we have to carefully consider how to do it.

The “Label Rate” on a pesticide label is usually given as a factor of active material per hectare/acre, combined along with a concentration rate to give a total combined material output per hectare/acre. So we could adjust either the active material or the total combined output.

Concentration rates are developed to provide a certain amount of coverage over a given surface area.

In cases like when spraying oils that need to surround and suffocate, or materials that need to be washed into small spaces, having enough water to provide that proper coverage is essential. Other materials are called systemics, which means that the plant absorbs the active ingredient and distributes it through tissue movement. We refer to this as the “mode of action” of spray material, and it is important to consider.

Therefore, if your total combined foliage/crop is more/less than average, you should adjust your total combined material output to compensate for the change in the total surface area you now have to cover.

If your foliage/crop load is average but your disease pressure/environmental factors are high/low, you might consider adjusting the concentration of active ingredient so that your application will be stronger/weaker over an average canopy (bear in mind that some products like sulphur can burn if concentrated too much!).

All this spray saving information comes with a caveat – you must adjust your sprayer for the job each time you adjust your output! If you don’t aim your sprayer at the target (your plant) then you are sure to miss every time! Even doing as little as adjusting the sprayer setup once a year can provide huge material savings.

How do you set up your sprayer to save then? Luckily adjustments can be as little as turning off a couple of nozzles or reducing fan RPM. If you want to know more please give us a call, we are always happy to advise you.