Here is a new Pest Alert from Heather Faubert with URI Cooperative Extension.
To Fruit Growers:
Eggs on monitored trees in other towns have hatched, It is too late now, in most areas, to spray an insecticide to stop winter moth caterpillars from entering buds, except maybe in cooler areas, such as Little Compton.
On April 23 I observed many winter moth caterpillars inside of unsprayed apple and pear flower buds. Once caterpillars are inside buds they are protected from insecticide until buds open. For apple trees, the next opportunity to apply an effective insecticide is at Pink, when flower buds have separated, but before blossoms open.
This week I intend to pry open many sprayed apple and blueberry buds to see if winter moth caterpillars are inside. When looking for winter moth caterpillars, mostly what you look for is the caterpillar frass – caterpillar poop. When caterpillars are small they can be very difficult to find. Frass in blueberry buds is black, but frass in apple buds tends to be brown or orange-brown.
Once the blossoms are open, check for evidence of sufficient larva to warrant treatment. If needed, the Organic Materials Review Institute (ORMI) has approved the use of DiPel or another Bt (Bacillis thuringiensis) as well as Entrust and Neemix.