@scottfsmith can I ask where you buy your grandevo?
Thank you
Grandevo, Venerate, and Madex I all got from Seven Springs.
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Are any of the new insecticides effective for PC? I have not had the time to focus on this the past two years. Still using permethrin and Imidan.
Is there a good guide of when to stop spraying for PC? How do you know when the danger is past? Time? Fruit size? Never?
You need to check whether there is one brood where you live or a second coming along later. In which case, probably never
How do you check this? Through the local extension website or is there something better? My local extension (PSU) seems to focus on publishing updated info on Apple pests.
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Good question, I would like to know too. I saw couple of PC bite marks on my plum yesterday. I know they are out and active now. I went out last night while the wind was calm and no bees and prayed the trees with Marathion.
Did you mean malathion? Does that work well? I just have an old bottle of permethrin that iām going thru. Seems to work ok, but iād like an alternative. This is a lot of years in a row of spraying the same stuff.
Going to be a tough year with the curculio here. Didnāt have great return bloom to start with, and it was colder than hell through most of the apple blossom period, so pollination was poor. All adds up to a very thin fruit set. Then to further complicate things, we got socked in with days of on and off drizzle just when the temps finally came up enough for the curculio to become active. Iāve been trying for 2 days to get some Surround stuck onto the plums and apples that have fruit, between showers. Starting to see some egg laying as of this morning in the plums.
Generally I donāt spray the plums above 10ā or so, to leave a nice trap crop for the curculio Iām trying to discourage off the apples and rest of the plums. Surround works much better when you give the curculio an alternative host nearby. But there isnāt much fruit up there this year, so I may have no meaningful target for them, which will mean they pound that thin apple set even harder.
Iām expecting this to work out not to my liking.
I actually donāt really quit, because roughly the time when the curculio are done is just a fortnight or less before I have to have Surround coverage on the apples and pears for codling moth. So, I lay off the plums and cherries, and add pears to the Surround spray list roughly 6 weeks after the first curculio egg laying appears. The apples are therefor covered for any late arriving curculio, and the few plums I lose arenāt of much consequence.
Yes, malathion. auto spell corrections must have corrected me automaticallyš. It labeled for PC. I think it works as long as it is used at right timing. I donāt have a lot of pest pressure this year. Not sure this yearās strange weather pattern somehow influenced the pests population or I am heading to a heavy battle later. Either ways, so far all look good
Scott, our N. of Baltimore grower, recently posted that he deals with just one generation of PC and was sure I too (further south in Md) only had one. He said places much further south (of Md) could have two generations. So it seems to me youāll have only one generation of PC.
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Cornell has modeling software which is free to use for plum curculio and other insects. You could take a look at and see if it would be helpful to you. I have been using it some this year. One advantage is you can specify a local weather station like a nearby airport and it will give you results based on the local station.
Here is the link-
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Iām with you here, but mainly just because my sprayer does not have an agitator. I have to premix the surround. New sprayer is on my āwish listā now. 
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Do you find how accurate the model is ?
This is a long thread. Most of questions have been answered upthread. Re. PC and fruit size Scott Smith gave his answers on post#27 and #30.
I am in New England, UMass says we have 1 generations of PC, 2 generations of coddling moth and 3 generations of OFM. In other words, I canāt just focus on PC and stop spraying when PC move on (about a month) as I have CM and OFM who want my fruit, too.
I used to spray spray every 10-14 days and found that it was too long an interval. I now spray every 7-10 days for 3-4 times until fruit are big enough to bag. Fortunately, I have not many trees so bagging is doable.
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Iāve found that surround isnāt sticking to plums worth a damn. Sticks to apples, peaches, nectar, and euro pears fine, but just seams to sheet off of plums and Asian pears.
Emerald Beaut is hit very hard in my orchard. Looks like PC scars on almost all fruit. Even harder than Nadia
David,
I thought you sprayed with Imidan. That should work well.
I sprayed with imidan Wednesday night and after looking at the trees yesterday decided to add some surround. I had previously sprayed surround, imidan, and indar a few weeks ago but the nights were cold and the fruit size was much smaller.
The surround seemed to perform better on the pea sized plums. Now that the plums are grape sized itās almost like they are waxed. The surround just appeared to sheet flow off of them. Could it be becuase I sprayed them the night before with imidan and a sticker?
Locally I donāt know yet. I think I will need several years to really see how accurate it is locally. But you could probably find some literature talking about how accurate it is. Cornell gives this as reference for the model-
Plum Curculio
Reissig, W. H., J. P. Nyrop, & R. Straub. 1998. Oviposition model for timing insecticide sprays against plum curculio (Coleoptera: Curculionidae) in New York State. Environ. Entomol. 27: 1053-1061.
It seems the model counts degree days from biofix to determine how active the plum curculio are. It has a default value which for this model is the estimated time of petal fall for apples at the local weather station you use. You can input your actual date of petal fall which should help make the model more accurate.
Cornell info page for biofix
http://newa.cornell.edu/index.php?page=default-biofix-dates