With all the rain, frost, and wind it has been a challenge to squeeze in all the spring applications. We have been getting questions from growers about tank mixing compounds to save on time and reduce the number of chemigations. We don’t have a lot of experience on mixing cranberry compounds together – especially those from different classes (fungicide + herbicide, etc.). It is likely that many things we use are compatible, but there have been instances where issues arise from mixing compounds. For example, HPPD inhibitor herbicides like Callisto are known to cause crop injury if you mix them with organophosphates like Diazinon or carbamates like Sevin – or even use them in sequence too closely together. Avoid mixing compounds if possible and if you are experimenting with mixing compounds – use caution and start small. Let us know about your experiences.
Insect Management. Very high weevil numbers (50+) were found in sweeps on some beds in Wareham last week before the cold and rain set in. Some growers were able to successfully treat with Fanfare or Actara. In addition, green spanworm has been found in some bogs, generally small counts, but occasionally higher numbers were found. In the lab, we have already had 2 spanworm starting to pupate (but 100’s that are still small and eating). Cutworms, like false armyworm or humped green fruitworm, have been found in Middleboro and occasionally other spots. None over threshold but more occurrences than in past several years.
The hemiptera, black bug and leafhopper, have been found on cape bogs and some mainland bogs. They are at 2nd or 3rd instar, with black bug nymphs going from yellow to green now.
Once the rain subsides, and some temperature returns, it will be worth assessing what insects are out there and trying to manage them. Do not delay, we are rapidly moving into June and many advanced bogs are already approaching hook stage.
*Avaunt has some weevil resistance
**Fanfare and Actara are both restricted use compounds. Note 100-day PHI for Fanfare if export.
Weed Management. Dodder has been germinating for a few weeks now. If you have beds that have had dodder problems in the past, scout for seedling and make a management plan. Some growers are still applying Casoron, but remember that it should ideally applied when soil/air temps are under 60°F and then immediately incorporated by irrigation to move it into the soil. Cranberry plants become less tolerant to Casoron the further out of dormancy they get.
For dodder management, Kerb and QuinStar have good crop safety and have a little flexibility on timing. They can be used preemergence or early post-emergence (after the dodder germinates and is seeking a host to attach to). For dodder control, an early season application of QuinStar in late May or early June (when dodder is germinating and beginning to attach to cranberry), followed by a second application in July after cranberry bloom seems to be the most effective.
The how/what/where/when of QuinStar is a topic of much discussion. Quinclorac is absorbed by germinating seedling, plant leaves, and roots. This herbicide has a lot of flexibility. It can be effective as preemergence and also as a postemergence. Some growers have good success with two early seasons apps (April and May), some use an early season app and a second app after bloom, while others have only used a single app (either early or late). If you are using it early season and trying to get it into the soil for root absorption, you don’t need an adjuvant. If you are using it when the weeds are present, you should include an adjuvant (2-4 pt/A). Quinclorac is not a fast acting herbicide. Perennial plants can take weeks or even months to show symptoms.
Different grass species are actively growing and can be treated with grass herbicides (sethoxydim/Poast and clethodim/SelectMax, Intensity One, etc.). But poverty grass is still just hanging around, waiting for warmer weather. If you have multiple grass species with different active growth windows, you can treat them at different times.
We do NOT recommend using clethodim products during roughneck. When used during this cranberry growth stage it can cause some floral deformities that usually show up as fused petals (flowers never fully open). Howes are especially sensitive.