Crabapple scab and Japanese beetles

Hey all,

I have a customer in Iowa who informed me that Japanese beetles have been attacking her crabapples for a few years now as well as having a case of apple scab from the fungal infection Venturia inaequalis. I called treestuff and they put me in contact with their head chemical guy and we had a really good conversation and he pointed me in the right direction as far as products are concerned.

But I have a question: Has anyone mixed the fungicide/insecticide of Propiconazole 14.3 and Imidacloprid 2F to kill 2 birds with one stone and treat them at the same time?

Or should I treat them separately? How many treatments of each? At this point I know the existing leaves are more than likely already infected with scab, but spraying now would keep it from getting worse, then we would get ahead of it next spring at leaf emergence for the next few years.

However, how many treatments to kill the Japanese Beetle? I was told they're easy to kill, but should I keep treating for Japanese beetles on the same 7-10 day cycle that treating for scabs calls for?

Sorry for the noob questions, I'm starting to get into PHC more now that we're treating for EAB, and the profit margins are higher than regular treework and its not nearly as dangerous or physically demanding so I'm really starting to see the benefits of adding this element of Arboriculture to our business model.


Well-Known Member
Different issues at different times. It would be smart to learn the how why and when of pests and diseases prior to treating anything. Cultural practices are also extremely important before starting chemical intervention. My well mulched, watered, and pruned crabapple loses apprx 20% foliage to scab and japanese beetles a year.

That said youre too late to treat scab and likely too early to treat beetles unless youre in the southern part of state (st paul mn here no activity until mid/late june). Beetle damage here is also mainly cosmetic and treating with insecticides has consequences.

IPM and PHC should also revolve around the tree owners informed level of damage tolerance. Some people choose to have a slightly less full tree knowing fungicides and insecticides have an effect on pollinators

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