Things to think about regarding pesticides.
Keep an eye on PHIs. As we enter August, be mindful of each pesticide’s pre-harvest interval (PHI). Depending on when you harvest, you might be approaching the end of your application windows for the use of some products – especially for herbicides like Stinger (50-day PHI), Poast (60-day PHI), and QuinStar (60-day PHI). If using Ridomil for a late summer phytophthora application, know it has a 45-day PHI. Also keep in mind that handlers may impose a longer PHI than the product label. For example, the insecticide carbaryl (Sevin, etc.) has a 7-day PHI on the label but most handlers have a 75-day PHI!
Pesticide reports. Start thinking about getting your pesticide report into your handler (most are due August 30th)!
Insects.
Several reports and confirmed cases of Southern Red Mite (and its damage) on bogs came in this week. Both multiple weeks of 90+ degree temperatures and the widespread use of Fanfare surely contributed to this pest getting going. If you note off color vine (bronzing), mites might be the culprit. Look for white cast skins and tiny, tiny red dots on the backsides of leaves.
If you are planning on a final Delegate spray, now is the time. The second peak of Cranberry Fruitworm moth flight, and thus egglaying, is now. Summer generation Sparganothis are likely hatched and feeding, but too small to find.
It is likely too late to chase Cranberry Weevil. Reports are that numbers are down and the adults have left the bog to overwinter in the woods. Unless you detect very high numbers (30+), it is not economically reasonable to treat for them. Cranberry Flea Beetle may start feeding on overgrowth but unless very high numbers are found or significant damage is seen, the cost (and trauma) of a Diazinon spray, the only management option, may not be justified.
Weeds.
Some species of grass are still actively growing, so if you have grass on your bogs that has not yet flowered/made seeds you might want to do another application of a grass herbicide.
Growers have brought in and sent pictures of a grass that seems to be more prevalent this year than usual. Andropogon glomeratus, commonly known as bushy bluestem or bushy broomsedge, is related to one of our poverty grass species (Broomsedge bluestem; Andropogon virginicus). Unfortunately, by the time you notice the distinctive spikey looking stems, what you are seeing are the inflorescences (flowers/seeds) and the grass herbicides will not be effective. One grower I talked to was going to try to wipe the plants with Roundup (before seeds matured). If you have problems with this grass this year, I would be interested to know! kghantou@umass.edu or 508-970-7634.
Pictures of bushy bluestem (Andropogon glomeratus). Photo credit: Nan Hampton, Lady Bird Johnson Wildflower Center
