The Cranberry Station is closed on Friday, May 15, 2026.
Late Water Bogs. For those of you holding water, the water should be coming off soon (likely by May 15). Remember that the frost tolerance will be 29.5°F as soon as the flood is removed, no matter what the buds look like.
Insect Management. The cool weather and many frost nights have kept the insect populations remarkably low. Very few insects have been found for the intrepid sweepers who have been out. A single weevil can be found in a sweep here and there. A rare small green spanworm can be found here and there. A few collembola (not a pest) can be found amongst the spider and leaf litter. Tiny, tiny, tiny,1st instar blunt nosed leafhoppers were found on the cape but could only be seen with the microscope. No black bug have been detected anywhere. With the forecast, 70-degree stretch expected to begin this weekend, next week will be another story!
Weed Management. Since the granular herbicides Casoron and Evital are very expensive products (and can sometimes be hard on cranberry vines when broadcast applied) they are good candidates for use as spot applications. I have had several growers ask how to estimate the right rate when using the granular herbicides in small areas.
Casoron and Evital have very different weights per volume from one another. Evital is much heavier.
- Evital: About ½ teaspoon per square yard will approximate 80 lbs/A (1 tsp will be around the max of 160 lbs/A).
- Casoron: About 2 teaspoons per square yard will approximate 60 lbs/A (3 tsp will be close to max of 100 lbs/A).
- Casoron should ideally be applied before budbreak to ensure crop safety.
If the cranberry buds are near or beyond cabbagehead, it is too late to apply Spartan (sulfentrazone) without a risk to crop safety.
Now is the time to plan preemergence dodder control.
- Casoron: should be applied preemergence (after you note the first emergence of early sprouts) and be present as the seeds germinate on the bog.
- Kerb: is effective when applied either preemergence (before most seeds have germinated) or early postemergence (after the seeds have germinated but before they attach to a host).
- Quinstar: can be applied preemergence to early postemergence. It is likely more effective if a second application is made (at least 30 days between apps). Some growers find making the second application in July to be very effective.
- Mesotrione (Callisto, Explorer, etc.): This herbicide does not inhibit dodder seed germination and is probably not effective for dodder if applied too early. Control will improve if the application is timed for early postemergence when the seeds have already germinated but are yet not securely attached to hosts.
Many growers continue to have questions about what the best timing for grass management- and my answer is always “it depends”. There is no single perfect timing because there are so many different grass weeds out there. Remember that the clethodim products (Select Max, Intensity One) work on ACTIVELY growing grass – those that are getting bigger and adding biomass. For poverty grass, that stage doesn’t happen until much later in the season (July), but for other grasses it can be happening now. Feel free to call me with any questions about timing, identification, or any other issues call Katie 508-970-7634.
Disease Management. The upcoming week is an important timing window for Upright Dieback management. Fungicide applications should target the period when new growth has begun (from cabbage head through elongation stages) but before roughneck stage (see images for reference).
Chlorothalonil remains the preferred option for Upright Dieback management. Growers producing fruit for export markets should remember that chlorothalonil has a 120-day preharvest interval restriction associated with export requirements.
Many disease issues, including Phytophthora root rot, are also related to or aggravated by poor drainage and prolonged soil saturation. With the recent series of frost nights and associated irrigation events, some beds may remain excessively wet. If possible, take steps to improve drainage and avoid prolonged saturated conditions.
If you suspect Upright Dieback, Phytophthora root rot, or have any disease diagnostic or management questions, please contact Leela Uppala 508-970-7644.
Soil fertility. Potassium (K) is the nutrient that is associated with improved plant turgor/hydration, so products containing K have been the classic choice for spring applications (Sul-Po-Mag, potassium thiosulfate, RE-NFORCE K, etc.). The cation exchange complex in the soil holds Ca, Mg, and K. So, adding Ca and or Mg along with the K is intended to maintain a good balance.
Some growers are choosing to add some nitrogen early in the season. Remember that when N is applied pre-bloom, it is rapidly taken into the plant and moved to the new leafy growth. Adding too much N at this stage can lead to excessive growth, so start small.