Many growers that experienced winterkill or other winter stress are choosing to provide some nutrient support to the vines are they are coming out of dormancy this spring, using products like Sul-Po-Mag (Sulfur, Potassium and Magnesium), Solu-cal, RE-NFORCE® K (5% nitrogen, 20% potassium and 13% sulfur), or other similar products.
For those of you holding late water (LW), remember that the frost tolerance will be 29.5°F as soon as the flood is removed, no matter what the buds look like. Casoron can be applied for dodder control after the flood is removed but wait for the bog to fully drain before applying. You still need to scout your LW bogs for spring insects, even though you will likely be able to omit the early insecticides. Nitrogen needs for the vines are usually less on LW bogs, so you can usually skip your first N application and/or reduce the fruit set dose. It is best to wait at least 2 weeks after flood removal and add small amounts and monitor the progress of growth. Generally, no fertilizer is needed before bloom but go out and look.
Insect Management. The bugs have begun! Weevil are definitely active on the bogs now, especially on days that approach 70 degrees. Most growers are picking up only 1 and 2 per sweep set, but some hot spots have already seen 20 count!! Avaunt, Actara and Fanfare are your options for this pest.
Black bug has also been sighted. The very small green nymphs are hard to see, but they have hatched and are out there. If you are targeting Black bug, acetamiprid (Assail or Arvida) is your best bet (but it won’t help with weevil).
Green spanworm has also hatched and is being picked up in sweeps at one or two counts per set in some cases. You would need a lot more to warrant a spray of Avaunt (running at around $40/A per app)! An elusive unusual fat false armyworm cutworm has even been seen. Plan to get out on the bog next week to check your acreage for activity. Scale damage can be seen amongst the winterkill.
Disease Management. If you have problems with upright dieback or Fairy Ring, it is time to think about management options for those diseases. For upright dieback control, chlorothalonil or copper applications at bud break and/or early bud expansion are known to provide excellent control of the disease. Time the application for when the bud has broken dormancy and new growth has begun (elongation period prior to roughneck). The first fungicide application for Fairy Ring control is also timed for budbreak. A combination soil drench of Indar and Abound is recommended. Please see the Chart Book for details. If you suspect Phytophthora root rot or have any other disease diagnostics or management questions, please reach out to Leela Uppala: 508-970-7644
Weed Management. There are now reports of dodder seedlings germinating on bogs (first reported on May 6th). Scout your bog to time herbicide applications for dodder. Search in the canopy and/or in areas where you off-load your fruit and trash. These are the best places to find dodder seedlings. The window for Casoron use (which acts primarily to inhibit seed germination) is quickly closing, as applications should be made before budbreak. Growers using QuinStar to manage dodder should plan an early season application in May (when dodder is actively germinating and beginning to attach to cranberry), followed by a second application in July after cranberry bloom was effective for control. We have renewed the Emergency Exemption aka Section 18 label that allows growers (MA only) to use Kerb for dodder control (new label valid April 15-June15 2025).
Kerb provides both pre-emergence and early postemergence dodder control. It will inhibit the “searching” ability of the dodder seedlings such that they cannot successfully attach to a host. Handler restrictions will likely apply. Remember that Kerb is Zone II-restricted. If you are in a Zone II, please call Katie at the Station to determine if you qualify for a letter. You cannot apply Kerb in a Zone II without a qualifying letter.
The window for sulfentrazone products is likely closed for most (if not all) growers at this point. Do NOT apply Spartan if your buds are near cabbagehead or beyond, or you will get vine injury.
Many growers have been questioning the best timing for grass management. The answer is - there is no single perfect timing! The answer is it depends on what you are trying to manage. The herbicides that target grass (like Select Max or Intensity One) work when the grass is ACTIVELY growing (getting bigger, adding biomass) but before they flower and make seeds. There are definitely some species of grass that are actively growing now, but many others like Poverty Grass will not be actively growing until later in the summer. You can make multiple applications, so if you have many different species of problem grasses that are growing at different points in the season, you probably need multiple timings. Always include and adjuvant and remember that clethodim has NO soil activity. Keep as much of it on the leaves as possible.