Plum curculio - timing of emergence and attack

Plum curculio emerge in the spring and then go on the attack against young fruit on trees. IIRC, the timing of PC emergence can be estimated fairly accurately using a degree-day model.

Is it correct that at some point after the time of emergence (e.g., a few weeks, perhaps) PC attacks on fruit begin a steady decline?

Is there some rule-of-thumb that PC emergence generally follows? For example, is it usually fairly coincident with apple blossoms falling off the trees?

If someone could help me raise my level of understanding of this subject, that would be great.




I think PC operates a little differently depending on climate. Here they emerge around the time of shuck split on peaches, or maybe a little before. They supposedly stay around for 5 to 7 weeks, but practically speaking they don’t, because I kill them. :smile:

Egg laying is the main damage they do, but they also cause what eventually becomes catfacing damage, by their feeding.

I don’t spray until shucks off for peaches because the shuck provides decent protection against PC (as well as stink bug). This timing generally coincides with petal fall of apples around here. Sometimes I wait a little too long and get some egg laying on plums (which of course is their preference). The beetle doesn’t like hot weather which suppresses egg laying. Generally I don’t have to worry too much about second generation larva here (in July or early Aug.) Still I’ve gotten some PC larva in peaches if I just use a targeted spray for Oriental Fruit moth which won’t also kill PC in the summer months, so I don’t use just sprays for OFM in the summer for prolonged periods. Instead I rotate something which will also kill PC in the summer.


I just noticed this thread here Multi variety orchard spray plan where there is a discussion going on now about PC with lots of good info.

I just sprayed mine today much. My peaches are just past shuck split, but I pushed it a bit until all the blossom was gone from everything else just to prevent killing any pollenizers and so I could spray everything all at once. Probably a bit early for other stuff, but I wanted to get some myclo on the apples. I’ll hit them again soon.

Seeing that were fairly close, you probably need to get going with the spray I would guess.

Olpea…good point about the shuck providing some protection. I never thought about that before.

1 Like