Because of the wet spring this year, we saw a significant increase in leaf scab on pear trees throughout Suffolk and Nassau counties. This caused a certain amount of leaf drop in unprotected trees, but most trees were able to hold onto their leaves and push out new ones. We had a lot of luck with trees that were on a program to get regular protective fungicide treatments starting in early spring. Those trees held onto their leaves and did OK. The trick with fungicide treatments is that you have to get them on when the buds open and the leaves spread out, in order to coat and protect the surface tissue (cuticle) of the leaves. Pear trees are among the first trees to open up their buds in the spring, so we usually recommend at least 3 treatments starting when the buds break (late April/early May.) This way, as the leaves grow, the tender growing new tissue is getting coverage.
A new threat has emerged in Rockville Center, which will surely make it’s way east – Pear trellis rust (Gymnosporangium fuscum) which needs two alternate hosts to complete its life cycle. It overwinters on the twigs of juniper species and in early spring it infects newly developed leaves of pear trees. Right now it seems to be more prevalent in Bradford pears, but it can attack all varieties. Unfortunately, most fungicide treatments have not been shown to be particularly effective (unlike treatments for pear leaf scab,) but there are several materials which are labelled and look promising. One recommendation is to remove nearby juniper bushes away from valued and significant pear trees or groves, which may not always be practical.
Fox tree Service highly recommends treating your pear trees against scab and other diseases ion order to keep them vigorous. Healthy trees tend to weather insect and disease outbreaks better than trees that are in poor shape. Call us today to arrange treatments this coming spring.
Here is a link to a broadcast news story about trellis rust in Long Island: http://newyork.cbslocal.com/2017/09/25/pear-trees-trellis-rust/