This year is a little weird, I can’t decide under these temperature (current and forecasted), should I spray for PC, OFM, CM, stink bugs? What would you do, wait or spray now?
Pear, plum, cherry, apricot are all in, or passed shuck split
I am in central Illinois on the zone 5/6 border. Tart cherries are at 20-40 % of the shucks have dropped. Apples are in petal fall or early fruit formation. I am going to spray this week on a dry day with fungicide/insecticide.
With all the rain I think you need to get fungicide on the trees at the very least. But I think it would be best to spray an insecticide too. Temperatures can swing wildly and forecasts aren’t always accurate. Next Wednesday it could have a daily high of 80F and be raining. It’s hard to spray in a down pour so I think it would be best to spray as soon as you can.
I am in Chicagoland. This spring is dry, very little rain. The leafs are healthier than last year’s. No blossom blight, no PLC etc. major spring time fugi infection so far. The fruits set well. In the past, by this time, I already had insecticide and fungicides sprayed.
My question is , with this kind of night temperature, does insecticide effective? I mean, are the PC, OFM, CM out there in activities? I understand that insecticides only good for 1~2days. If they are not out and in action, my spray of insecticides only kill the pollinators, most likely bumblebees which is active in cooler weathers. I am concerned
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Fungicides are mainly preventative with some exceptions. They need to be on the leaves/fruit before the fungi show up. Some like Indar have a curative effect but that is the exception and the curative effect is limited. I know from experience that once cherry leaf spot shows up even on a small number of leaves it becomes much harder to control.
For the insects there are models that predict when the insects become active. I believe Cornell has some models available that you can use. The models take into account the temperature history to predict when the insects are active and when they hatch out. I don’t use them myself. For plum curculio there is a thread that talks about the temperature ranges when they become active.
If the temperatures are low the plum curculio can still be on the trees but are less active. I think most of us start spraying at petal fall or shuck split. And if the insects are there when the temperature spikes you can end up with a bunch of damage very quickly.
What insecticide are you using? Different insecticides are good for different lengths of time anywhere from 1 day to 14 days depending on the insecticide. I spray Triazicide at a 10-14 day spray interval. I understand you don’t want to harm pollinators but all of your trees are out of bloom right? So the risk to pollinators should be low. I would take all of the normal precautions, don’t spray when it windy, take care to make sure overspray doesn’t end up on flowering plants and mow down any flowering weeds below the fruit trees.
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This is one of the reasons that I can’t decide to spray or not this year. I spray around shuck split too in the past. But this year, my apricots are in peanut size, sweet cherry, pears are in pea size, sour cherry, J plum are in shucksplit, but the temperatures are lower than what was in the past. In the past year, if I didn’t spray at this size fruitlets, there had been some % of fruitlets with insects damage already. But this year I didn’t see single insect bite.
Is it just less insects out there this year?