Happy Summer Solstice!
Percent bloom and percent out-of-bloom are measures of cranberry development.
- “Percent bloom” is used to time fungicide sprays and fertilizer applications
- “Percent out-of-bloom” is used to time fruitworm sprays
To calculate you must collect flowering uprights. Walk in a line and randomly select 10 uprights. Collect at least 4 sets of 10 uprights per bed to get a good representation. The more uprights you collect, the more confident you can be in your estimate for the bog. For each set of 10 uprights, count all the floral structure (open flowers, flower pods, pinheads, fruit).
Percent bloom
(open flowers + pinheads) ÷ (flower pods + open flowers + pinheads + fruit)
Percent out-of-bloom
(pinheads + fruit) ÷ (flower pods + open flowers + pinheads + fruit)
Insects.
Keep your eyes out for brown areas! They could be caused by golden casebearer or it could be drought stress. The tiny brown beetle has been reported at a few sites. Drought stress has also been seen and can look very similar to areas of insect damage. Irrigation is the name of the game this past week. Sparganothis and fireworm moths are flying now, but if you are seeing moths on the bog, they are most likely green spanworm moths. If you see ‘a lot’, plan to spray a bit earlier in May next year for the larvae.
Next week, make note of the % out of bloom to time effective fruitworm insecticides applications. Altacor fruitworm timing is 50% OOB or shortly after (often coinciding with 3rd fungicide) for most cultivars (EB and H can drag their feet). The cranberry fruitworm moths are looking for slightly sized up pinheads to lay their eggs on!
Disease.
The Final Keeping Quality Forecast for 2024 is “VERY POOR”. We obtained only 2 points out of a possible 16 to arrive at this keeping quality forecast for the 2024 Massachusetts cranberry crop.
Most growers are in or approaching the 7–10-day retreatment interval after their first fruit rot fungicide application. Bloom is moving fast with the heat! Getting out another fungicide ASAP may be the most important thing right now.
If using broad-spectrum fungicides such as chlorothalonil (eg. Bravo) or mancozeb (eg. Manzate Max, Dithane M-45) as part of your fruit rot fungicide regime, they are best used early in the possible infection period (when the maximum number of flowers are open). This corresponds to early to mid-bloom (nowish).
Follow all label instructions carefully, including application intervals, recommended rates, water holding times, and pre-harvest intervals. Be careful to follow the restrictions for maximum amount of a.i. per year AND the maximum number of applications for each compound. This is important to remember when you are using mixtures. For example, if you apply Abound with Indar and then apply Quadris Top both applications count towards your max azoxystrobin for the year!
Weeds.
Most growers are hesitant to spray herbicides during bloom for fear of damaging the flowers or stressing the vine. In general, if you don’t have to spray herbicides during bloom, it is best to avoid doing so. However, herbicide efficacy is often based on growth stage of the weed, so if you need to spray during bloom, you can usually do so without impacting the crop. We have not experienced or heard of growers having issues with using Intensity One or Callisto during bloom, and NIS appears to be safe for use with these herbicides during this timing too. Crop oil carries a risk of injury to plants and delicate flowers. Avoid using crop oil during bloom and any other time that it is hot and humid: [air temp (ºF) + relative humidity = +150].
Fertilizer.
Early fruit set fertilizers go out at 75% bloom, so some varieties may be getting close!
