Insects.
Cranberry weevil continues to rule the discussion this week. Several large growers report high worrisome counts of cranberry weevil. Actara is the only option at this point in the season but it has extremely high bee toxicity. You must wait until your bees are pulled off your property (likely starting this weekend) or be quite sure there is no bloom on your bog in order to spray Actara. In addition, be aware your native bumblebees may still be present on the bog and can be severely impacted by an Actara spray. Weevil damage is already apparent showing as pinheads with drill holes and aborted fruit. Be sure it is worth it to spray, as weevil will likely move off the bog in another week or two. If you have 10 or 20 counts when you sweep, it may not be worth it. If you have 40 or 60, it may well be.
After the 2 Altacor applications for cranberry fruitworm, Intrepid/Invertid is the next compound of choice if you think you have fruitworm or sparganothis pressure. We recommend saving the spray Delegate until the end of the month.
Disease.
Bloom moved quickly! Most growers have applied their 3rd or even 4th fruit rot fungicide spray by now. Remember that fungicides are effective when flowers are present, and once the fruit has set and begun to increase in size (mid-late July), fungicides are no longer necessary or effective.
Weeds.
As the cranberry bloom period comes to an end, growers are thinking about postemergence herbicides. These include popular compounds like clethodim (Select Max/Intensity One, etc.), mesotrione (Callisto/Explorer, etc.) and this year quinclorac (QuinStar).
Poverty grass is at an active growth stage, and the active growth period is the best time to apply a grass herbicide for maximum efficacy. If you can treat it at least twice, you will get better control. Repeat applications need to be at least 14 days apart and there is a 30-day PHI for clethodim products (and an even longer 60-day PHI for Poast).
Remember to ALWAYS include a surfactant with your grass herbicide – it is needed for these types of herbicides to work. We have historically recommended 1-4 pt/A of NIS for chemigation applications. The amount of NIS used with other types of applications is typically based on a percentage of the final spray volume and this info can be found on the pesticide label.
You can apply up to two applications of mesotrione (Callisto) per year. If you have not already made an application and want to squeeze in two postemergence apps, remember that apps need to be at least 14 days apart and there is a 45-day PHI.
I have heard some reports that dodder seems to be suddenly exploding on the bogs. Colleagues from NJ report that QuinStar works best for dodder when an early season application (soon after dodder germinates and begins seeking host plants) is followed by an application in July after cranberry bloom. A single post-bloom application did not seem to be effective for dodder control in the year of treatment BUT some growers feel they get control the year after they apply QuinStar.
A postemergence application of Callisto by chemigation for dodder seems to work very well for some growers and not at all for others! We are not sure if it is timing issue, surfactants, variation in the dodder itself, or another unknown factor that leads to such mixed results from bog to bog and grower to grower.
If your dodder is in isolated patches, you can do a spot treatment spray with concentrated Callisto. This has been demonstrated to be effective. We have the SLN label on our web site under Services/Pesticide Labels. Spraying before dodder flowers is much more effective than spraying after flowers or seed are present.
