I started this post 5 years ago, on May 5 2018, which was the first day I had plum curculio strikes. This year I had pc strikes in mid-March. I wonder why the extreme difference in dates?
This past winter, except for 1 polar vortex in late Dec, was very warm. Many things woke up earlier than usual.
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I wanted to try Actara against this year, but couldn’t afford it.
So I am alternating sprays of permethrin and malathion.
Correct me if I am wrong, but as contact pesticides, these sprays have to be sprayed on the PC to kill it, right? Once a contact pesticide dries on the tree and fruit, the PC will not die if they show up later and start walking around and laying eggs?
Look at this post where there is a long collection of hints on using Surround (somewhere in the middle, look for “general Surround spraying tips”):
It is not so easy to use but with practice you can get the hang of it.
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Triazicide at maximum recommend strength + NuFilm sprayed every 10-14 days has worked well for me this year. Reapply a few days sooner if there is a lot of rain followed by a warm and sunny period.
Do your first spray shortly after petal fall and then repeat until 21 days before estimated harvest date. Or whatever the PHI is.
Also wait to thin fruit until there is some “June drop” and then selectively thin the fruits that have bite marks.
That’s my strategy so far and the only thing that worked. My plan is to dial back until I’m using the minimum effective dose and then try to switch over to more organic options.
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I am working a similar plan. I don’t use Nufilm perse but a Pinene type that I believe is meant to be similar (Pls help me with mix ratios for Pinene II (Nu Film sticker)). We’ll see how it does. Currently, the apples have a good number of PC scars, the peaches not as many.
That Imidan is really effective. No doubt. Even takes care of inside damage - post bite. I think I only used it once . . . perhaps twice . . . last year - and we had so much beautiful fruit.
But - it is soooo stinky. And the powder so fine. It just screams “Dangerous”. Some others mention Avaunt. ? I don’t have to worry about any protection of fruit (too much) this year . . . cause there isn’t much! But, I wish there was another effective alternative to Imidan.
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I’ve been hoping someone would respond to this with perhaps some research links. At least one contact insecticide (not for use on edibles though) I’m aware of is supposed to kill them if they simply walk through it, Fipronil. It’s marketed as a defense against termites, I use it against yellowjackets. Spray an active in-ground nest with a very tiny amount of it and they’re done. Soak some hydrogel with drippings from some raw chicken, again with a tiny amount of Fipronil mixed in, let the foragers find it and take a piece of the hydrogel back to the nest. But anyway, you were asking about efficacy of the various contact insecticides commonly used against PC. I too would like to know if they kill only if sprayed directly on, or if the PC walks through or perhaps bites a fruit coated with it. Or lays eggs in I suppose… Will that kill them or does the contact have to be more direct?
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You asking a lot. Even when researched there are so many variable you can’t simply answer the question.
Note
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What @KSprairie bolded above was the question I was repeating. More of a general clarification of what the word “contact” typically means. I believe that for most it literally means just that, an insect walking through and coming into “contact” with will be controlled. Words in the article you shared like “half-life” and “residual” and “persist” would seem to concur with that. Unless they’re mainly referring to insecticides which require ingestion, Btk and Spinosad being ones I believe that to be true for? Nonetheless, it just seemed like a question worthy of a clear-cut and simple answer, to help folks who will search and find this discussion later.
That’s also assuming that PC is affected by “contact” the same as other susceptible insects. A pest I’ve never observed in any of my trees but I’ve sure seen the after effects of!
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Good questions.
Depending on who you talk to, insecticides can be divided into three categories (non-systemic, systemic and translaminar) Systemic insecticides travel throughout the plant, generally from root uptake. Translaminar means locally systemic. That is, it travels short distances. If some of the leaf is covered with a translaminar insecticide, the insecticide will travel throughout the whole leaf. Non-systemic is just on the surface of the leaf or fruit. It does not penetrate at all.
Non-systemic insecticides can either be contact or require ingestion (as in Avaunt, which mostly requires ingestion). Contact insecticides can kill an insect by either being directly sprayed on the insect, or sprayed on the foliage/fruit and have the insect walk on the foliage/fruit. Contact insecticides are designed to be absorbed through the cuticle of the insect.
There has been a lot of research done on half lives of insecticides, and how much wash off, when it re-apply, etc. All this is based on the idea to keep enough residue on the foliage or fruit to kill the target insect pest. Whether it be an ingestible insecticide, or a contact insecticide. As an aside, most contact insecticides will also kill if ingested by the insect, so there is overlap there. The key is that contact insecticides mainly kill by coming in contact with insect.
Systemic and translaminar insecticides generally kill by ingestion. They are in the plant or leaf tissues, and kill when the insect starts feeding on the leaves or plant tissues. Imidacloprid is an example of a systemic insecticide, which is easily taken up by the roots.
However, again there is a lot of overlap. For example many systemic and translaminar insecticides also can kill on contact, if there is enough residue on the surface of the leaves/fruit. But mainly they are designed to kill by ingestion.
Actara is an example of a translaminar insecticide, which can also have systemic activity. It’s translaminar if sprayed on the foliage. But if it’s in the soil, it can also be taken up by the roots and move throughout the plant systemically.
Fipronil is a systemic. It can kill by contact or ingestion, but I don’t believe it is labeled for fruits.
In terms of PC, it’s a pretty tough beetle and not super easy to kill. Actara has worked pretty well for me. We still get some scars, but because of it’s translaminar activity, it has curative ability. That is, it will penetrate the fruitlets and kill the PC larva.
Imidan works very well. It is a non-systemic, but still has some curative activity. That’s because it is so extremely lethal to PC, and is sprayed on much heavier (pounds per acre). Evidently, even if a very small amount leaks into the PC scar, it will kill the larva.
Avaunt is another insecticide commonly used for PC. It requires mostly ingestion.
My own experience is mostly with Actara. It has been listed as one of the most effective insecticides for PC.
We still have some scars using just Actara, so the last few years we’ve generally added a pyrethroid along with it. This results in no scars and also controls stinkbug as well.
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Did you mean Imidan?
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@Olpea In your post above you put Indar a fungicide. As Danzeb mentioned above maybe you meant Imidan or another insecticide?
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Is this PC damage? This is my first year getting significant fruit set on my nectarines, and I realize I’m probably late to the party on doing something about it.
No.it’s not PC damage.it looks like some type of disease
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How effective is Spinosad on PCs and codling moths, apple maggots? I’ve always bagged, but too many apples to bag this year. Spinosad has worked well on potato beetles and tent caterpillars be in the past. I mix Surround with the Spinosad for the pre-bagging sprays, but wonder if the Surround is redundant. Will they work all season if I spray weekly?
Looks Like thrip damage to me. It could also be some little beetle having a snack. If you don’t want to spray during bloom you will just have to accept some nectarines will look like this. You can also just grow peaches and not have this issue. The more fuzz the better (against thrips)
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Thanks! That’s good news I think. I don’t mind ugly fruit at this stage, just wanting to avoid things that will cause fruit drop like I had last year.
Excellent descriptions of the types of insecticides. Thank you so much Mark for taking the time to explain all of that.
I read and follow label directions, but I have not dug in and researched much about the details of how and why different classes of insecticides work. Or when I do, I can’t find answers to the questions I am looking for. I was questioning the efficacy of contact insecticides, and how long they persist on the leaf & fruit surface in enough strength to kill PC walking around. I read somewhere, but can’t find the source now, that contact insecticides that are available for home orchard use have very short half lives (breaking down quickly with sun exposure) and do not persist on the tree for as long as the wait period is between sprays. So basically if you don’t hit them with the spray, they won’t be affected much. And your fruit is therefore vulnerable for 7-10 days until your next spray, if you are spraying every 10-14 days. Which makes me think, what’s the point of using them? I am talking about malathion, permethrin, carbaryl mainly.
I don’t know where I read that, but it must not have been a reliable source, or I am not remembering correctly. I am not saying contact insecticides are the best choice to use, I don’t think they are for my situation, but maybe they are more effective than I previously thought. But if that is the case, then they are also more harmful to the beneficial insects. So any lady beetle, praying mantis, lacewing, spider, etc that walk around in the trees will die because they have come in contact with the insecticide residue? I want to increase beneficials, not kill them off. I am at war with the pests, but the beneficials are being killed just the same.
This is interesting, and not new information to most of you, but is something I hadn’t considered in many years. The substrate to which the insecticide is applied, also affects the half life considerably:
From National Pesticide Information Center: http://npic.orst.edu/factsheets/half-life.html
Each pesticide can have many half-lives depending on conditions in the environment. For example, permethrin (Permethrin General Fact Sheet) breaks down at different speeds in soil, in water, on plants, and in homes.
- In soil, the half-life of permethrin is about 40 days, ranging from 11-113 days.
- In the water column, the half-life of permethrin is 19-27 hours. If it sticks to sediment, it can last over a year.
- On plant surfaces, the half-life of permethrin ranges from 1-3 weeks, depending on the plant species.
- Indoors, the half-life of permethrin can be highly variable. It is expected to be over, or well over, 20 days.
Malathion
Bacteria in the soil may break down malathion and sunlight can break down malathion in the air. Malathion will mix with water and can move quickly through soil. Because of these properties, malathion can be found in surface waters such as streams, and sometimes it is found in well water. The time it takes for malathion to break down to half of the original amount in soil is about 17 days, depending on the soil type. This length of time is known as the half-life. In water, malathion has a half-life between 2 and 18 days, depending on conditions like temperature and pH. Malathion vapor may also move long distances in air or fog. From another source [Bradman MA, Harnly ME, Goldman LR, Marty MA, Dawson SV, Dibartolomeis MJ (1994). Malathion and malaoxon environmental levels used for exposure assessment and risk characterization of aerial applications to residential areas of southern California, 1989-1990. J Expo Anal Environ Epidemiol. 4:49.]: The half-life on plant surfaces is 1 to 7 days.
Carbaryl
At soil and water surfaces, microbes break carbaryl down quickly. Half-lives are 4 days in water and 16 days on soil surfaces. Sunlight can also break carbaryl down. When carbaryl was not broken down by water but was still exposed to sunlight, a half-life of 21 days was reported. Carbaryl has a moderate ability to dissolve in water and migrate through soil toward ground water. Deep down in soil, where oxygen is absent, carbaryl breaks down more slowly. A half-life of 72 days has been reported. In water and soil, carbaryl has a low potential to make vapors into the air.
When carbaryl gets on leaf surfaces, very little is absorbed into the leaf. However, carbaryl is more readily taken up by the roots and moves to areas of active growth. On leaf surfaces, a half-life of 3.7 days has been reported.
I read this article last week and was wondering what your thoughts were on the statement that organophosphates (malathion being one) can provide curative action up to 2 weeks after eggs are deposited. From Michigan State University:
(Effectively controlling plum curculio in stone and pome fruits - Fruit & Nuts)
There are many insecticides available for control of plum curculio, but their performance characteristics vary greatly compared to our traditional broad-spectrum chemistries. Conventional insecticides, such as organophosphates and pyrethroids, work primarily as lethal contact poisons on plum curculio adults in the tree canopy. Avaunt also works primarily by lethal activity, but ingestion is the important means for delivering the poison. Neonicotinoids are highly lethal to plum curculio via contact for the first several days after application, but as these systemic compounds move into plant tissue, they protect fruit from plum curclio injury via their oviposition (egglaying) deterrence and anti-feedant modes of activity.
The rotation of these two modes of action is critical to successful plum curculio control. Avuant needs to be used prior to any neonicotinoids because Avaunt must be ingested to work effectively, and the neonicotinoids have that anti-feedant characteristic. If needed use Avaunt first followed by neonicotinoid insecticide. Neonicotinoids and organophosphates (OPs) can also be used as rescue treatments because they have a curative action that can kill eggs and larvae that are already present in the fruit. If plum curculio infestation occurs and a rescue treatment is needed, organophosphates and neonicotinoids can provide curative action up to two weeks after plum curculio infestation, although in some cases dead cadavers can still be found in fruit. Growers should not rely on this curative mechanism for most effective plum curculio control.[Controlling Plum Curculio]
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Yes, I did mean Imidan. Sorry, hands typing faster than brain. Thanks for the heads up. I corrected my post.
Most contact insecticides are indiscriminate. They have a broad spectrum and will kill predator insects along with pests.
In my case, if I want to kill stink bug, I have to kill predators. If one wasn’t worried about stink bug a systemic or translaminar would probably be easier on the predators. Something like Actara or Avaunt would be easier on predators than a non-systemic contact insecticide.
Not that you won’t kill some predators with Actara or Avaunt, but it would be less than something like permethrin.
Most pyrethroids like permethrin don’t last a super long time. The problem is generally they don’t like heat and UV. Because of this issue Syngenta developed Warrior II (same active ingredient as Warrior - Lambda cyhalothrin) but with micro encapsulation. They encapsulate the active ingredient in something that protects from UV. Sort of a slow release, as I understand it.
Carbaryl is the same way, but even shorter half life on trees. Bayer developed Sevin XLR (stands for extra long residue). I don’t know how Bayer made it degrade slower, but apparently they did. The Sevin XLR is sold in 2.5 gal. jugs, enough for about 3 acres of peaches for one spray. So it would take a long time to use up with just a few trees.
Nufilm 17 spreader/sticker advertises their product microencapsulates with UV protection. Some people like Tactic. I’ve used both, as well as Latron B 1956. Who knows which one is best, but I will note that Nufilm 17 is the gooiest and hardest to wash off the tank or your hands. Based on this, my opinion is that Nufilm is probably the best. Right now I’m using Cohere (Helena Ag). They claim it also has a UV blocker, does not require sunlight to set, and will allow locally systemic (translaminar) products to penetrate leaf surfaces.
Again who knows which one is best? All the manufacturers make it sound like they have the best product. I think it’s safe to say, some brand of sticker/spreader is better than none.
For stuff which is subject to UV degradation, it’s probably best to spray as the sun is going down. There was someone on this fruit forum who successfully used Malathion for major fruit pests. He said his key was spraying at night.
I don’t quite think Malathion would allow 2 weeks curative action. In fact, I doubt Malathion would provide any kickback.
I suspect John Wise was referring to Imidan when he mentioned 2 weeks kickback. And possibly Azinphos Methyl (Guthion) which is no longer registered with the EPA. These are very powerful insecticides (especially Guthion) in which a very small amount is required to kill PC. I don’t think Malathion would be on the same level of lethality to PC, as Imidan or Guthion, even though they are the same class of insecticide (1B organophosphate).
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