Cranberry IPM Message

IPM Message for Cranberry Growers: May 28, 2016

Cranberry weevils, in numbers of 10-20 per sweep set, were reported late last week. Be on the lookout.

If you want to apply Poast (or Select) and Callisto at the same time, you must do a ground application. Poast and Select cannot be applied by chemigation and Callisto cannot be applied by air.

Many growers are picking up gypsy moth larvae; sweep sets easily in the 10’s and 20’s. The threshold is 4.5 average per sweep set but try not to jump the gun too soon. We are still early in the season and we haven’t seen any of the early season pests yet, like cranberry weevil and cutworms.

Gypsy moth larvae, sometimes up in the 20's have been reported. Winter moth is still a concern especially if the insect has been problematic on your bog in previous years. The long string of frost nights has made application of May pesticides difficult, however we appear to be heading into a better weather window. Devrinol applications can still be safely made. Some growers are putting out...

Some early grasses are up. Growers are spraying Poast and/or Select for control of these early emerging grasses. These herbicides work best when applied before grasses flower. Be sure they are tall enough to have enough leaf area to absorb the herbicide (usually 4-8" tall is a good guide). Grass herbicides CANNOT be applied through the chemigation system. They will only control TRUE...

Dodder seedlings (~1/2” long) were reported on April 25, occurring in a bog in Rochester. Applications of Casoron for dodder control will be going out soon. Be sure to check your own bog for early emerging seedlings. We have demonstrated improved efficacy with higher rates and/or two applications of Casoron (on a bog where control was inadequate).

Now is the time to be looking (and spraying) for winter moth larvae out on the bog! Advanced bogs, hybrid cultivars, and sanded bogs will be warmer and more likely to have growth that is appealing to WM now. These bogs will likely need to be sprayed this week. Later varieties and colder areas will likely need applications next week.

The weather has been and will continue to be very hot. This can be stressful for the vines. Monitor as needed to make sure the vines and fruit are not lacking for water.

If you have flea beetles out there and have numbers "too high" to count, you should spray Diazinon as soon as possible. Cranberry weevils (second generation) are out and abundant in some cases. The threshold for spraying is higher for the summer generation; an average of 9 is used to trigger a spray. Remember Actara is Zone II regulated and highly toxic to bees.

Early rot has already been reported on Early Blacks and Stevens. This fruit rot disease is one of the first to be observed during the growing season. Infected fruit have brown-dark brown spots with concentric rings and as infection progresses, black, pimple-like structure (pycnidia) may be visible on the fruit surface.

We have gotten a few calls about gypsy moth. There is no recommendation to treat for the moths that folks are reporting (both brown moths and white moths); IPM recommendations target larval stages. To the best of our knowledge, gypsy moth has only one generation per year, contrary to some information going around in the rumor mill. You may see dead caterpillars on tree trunks.

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