Alarming Pesticide recommendation!

[Fishman43]

I spent the past couple of days at a CCA (certified Crop Advisor) training for my “day job”. The very last presenter had some alarming recommendations regarding the delivery of pesticides that could possibly affect beekeepers.

In the fight against the spotted winged drosophila that has recently begun to invade the New England States, the recommendation is now to add sugar to the pesticide application (pyrithriods through neonics) to increase uptake by the flies. He claimed that at 1-2 lbs of sugar per 100 gallons of application the % is low enough to not attract bees, and that the application recommendation time is at ripe fruit so no flowers will be in the blooming on the treated plants. I see several concerns with that not the least of which are:

1. Who is enforcing only 1-2 lbs per 100 gallons. I can just see it now when a farmer dumps extra in because more must be better, or the sugar bags come in larger increments.
2. What about everything else blooming around the sprayed area the could/will catch overspray
3. What about the bees attracted to the dropped/split fruit in the spayed ripe fruit field
4. Etc
5. Etc

You get my drift, this is an alarming recommendation anyway you look at it! I know that the SWD is a major pest and one fruit growers really need to be concerned with, but my humble opinion is adding sugar to a pesticide spray is a terrible idea!

[jim lyon]

The delivery of what pesticides on what crops? This sounds alarming and really off label to me.

[Fishman43]

Any pesticide labeled for use on any crop that has an issue with spotted wing drosophila. The list is very, very long.

Blueberries
Raspberries
Strawberries
Peaches
Plums
cherries
grapes
etc
etc
etc

[Kieck]

I'm not sure that the sugar is intended as anything other than a "sticker." Commercial pesticide applications are usually made at 10 to 20 gallons per acre, or less than 5 gallons per acre if sprayed from a plane. At 20 gallons per acre, an observer would be hard pressed to see much liquid on sprayed foliage immediately after spraying. The thin film of liquid that can be seen really appears at applications greater than 45 gallons per acre.

I doubt bees would be attracted even if growers dumped 20 pounds of sugar per 100 gallons into the tank and applied it at 20 gallons per acre. That would work out to four pounds of sugar spread over one acre. The greater risk is from increased pesticide use in general.

[jim lyon]

Then why not crop oil instead?

[Fishman43]

Kieck you may be correct on all but the "sticker" reason. It was clearly stated that having the sugar in the mix caused the SWD to "taste" the material thereby increasing uptake. They have apparently tested salt as well with similar results on uptake by the bugs, the problem was the salt is hard the equipment and builds up in the soils to quickly. There are plenty of surfactant and binding agents mixed in with applications already to keep them stuck on the plants, the sugar was just to increase uptake.

The spray rates are going to be higher to target SWD as well since it needs to coat the ripe fruit as that is what the adults are attacking. With the high pressure or high volume sprayers needed to get sufficient coverage there is going to be dripping quantities of liquid. It may dry quickly, and the recomended rates may be lower than expected, but it is still disconcerting.

[Fishman43]

Then why not crop oil instead?

I don't follow the question?

[Kieck]

Crop oil interacts with some chemicals, won't mix properly with some chemistries, has some toxicity issues of its own and is more expensive than sugar.

Some guys have added sugar to their tanks while spraying for aphids around here for years, claiming it helps the pesticide "stick" to the crop plants.

[Kieck]

Kieck you may be correct on all but the "sticker" reason. -Fishman43

"High volume" is 20 gallons per acre. If you read the labels for the active ingredients that can be used against SWD, you'll find that all list upper limits of active ingredients per acre. That doesn't change, even if the amount of finished product to be applied does. What I mean is this: if the maximum of an active ingredient is 6 ounces per acre, you can mix that 6 ounces in 10 gallons of water and apply that to one acre, or you can mix it in 20 gallons of water and apply it to one acre. The amount of water changes. The amount of pesticide does not. Most applicators prefer to apply at lower rates because hauling that much water through a field/orchard is costly.

What you wrote about the "tasting" is true, but maybe not in the way that most people envision it. The flies (SWD) don't have to drink the pesticide to die from it, but die by having it come into contact with their mouthparts and therefore having it be ingested in trace amounts. Tiny residues of sugars involuntarily cause the Drosophila to extend their mouthparts and sample what they're standing on (they detect "taste" through their "feet," first).

http://www.ct.gov/caes/lib/caes/docu...swd_locked.pdf

But let's just exaggerate numbers a bit to see where it goes. Let's say that some producer put twice as much sugar as is recommended into his tank. Let's even round that up, just to make the math more convenient. The recommended rate is 1 to 2 pounds per hundred gallons. So, let's say that the producer dumped a 10-pound sack of sugar into a 200-gallon tank (5 pounds per 100 gallons). Then he goes out at applies at 50 gallons per acre, which is a rate that someone with a hand sprayer might use if he kept spraying until liquid makes leaves look shiny so he "knows" he's killing his intended pest. At these rates, we're talking about 2.5 pounds of sugar over one acre, or 0.0009 ounces of sugar per square foot. And that's doubling (and then some) both the concentration of the sugar, and the amount of applied product.

[JBJ]

Perhaps relevant here, a piece on honeybees taste perception thresholds:
http://chemse.oxfordjournals.org/con...se.bjr040.full

"The response threshold of these sensilla was below 0.1% as they responded to a sucrose concentration of 0.1% w/w"

[jim lyon]

Dosent crop oil also serve to allow for lower application rates because of better adhesion to plant surfaces?

[deknow]

The question is, what is the sugar concentration of the dried residue.

Deknow

[jim lyon]

I am thinking the recommendation to add sugar is to attract the target insect (flies) and if the rate is high enough for flies is it also high enough to attract honeybees in certain situations. If it is strictly for adhesion that seems kind of curious as isn't this the same problem that applicators have dealt with for decades. Why now sugar?

[Kieck]

The question is, what is the sugar concentration of the dried residue. -deknow

Very, very high, I would think, but it's hard to measure. In the tank, applicators mix water, pesticide, adjuvants, surfactants, etcetera, including sugar. Once it dries, the bulk of it is gone.

Think of it this way: if you put a three grains of table sugar in a beaker, and fill the beaker with distilled water, the concentration of sugar is very low. However, once it's dried (i. e., the water evaporates off) only the sugar is left (theoretically, at least). The concentration of that sugar is 100 percent. Again, that's assuming theoretical, perfect conditions.

In the spray, the active ingredient(s) and the other components that do not volatilize, evaporate, or move into the plant would "contaminate" the sugar.

If you spread 0.0003 ounces of sugar evenly over one square foot, will it attract bees? I'm not sure.

I am thinking the recommendation to add sugar is to attract the target insect (flies) and if the rate is high enough for flies is it also high enough to attract honeybees in certain situations. -jim lyon

It's a bit different, I think. The flies are landing on leaves, fruit and so on, as they identify and approach resources (fruit) that appeals to them. As soon as they land, chemosensors ("taste buds," if you will) in the structures of their "feet" sense the sugar and cause a reflexive reaction that extends their mouthparts to taste what their "feet" taste. The flies aren't attracted to the spray, I don't believe.

[Fishman43]

It's a bit different, I think. The flies are landing on leaves, fruit and so on, as they identify and approach resources (fruit) that appeals to them. As soon as they land, chemosensors ("taste buds," if you will) in the structures of their "feet" sense the sugar and cause a reflexive reaction that extends their mouthparts to taste what their "feet" taste. The flies aren't attracted to the spray, I don't believe.

Correct, and the reason that the research showed similarly good results with salt in getting the flies to use their mouthparts for a taste. It is an involuntary response by the flies to lower their mouthparts when their feet sense a potential meal. The fruit brings them in as a host for the larvae, the sugar triggers a feed response, the feed response creates a better delivery of the pesticide.

[jim lyon]

Is the use of sugar in tank mixes something new?

[Fishman43]

It certainly is in my area. It seems that Kieck has indicated it has been used in his area for a while (post 8) for the treatment of aphids.