Southwest Michigan vegetable regional report – August 3, 2016
This is the week vine crop plantings could be at risk for downy mildew.
Harvest has continued on all crops with no weather interruptions. All vegetable crops are now being harvested with the exception of fall squash and pumpkins.
Vine crop growers should apply protection for downy mildew. Spore counts at the Southwest Michigan Horticulture Research Center went up on July 20 and the cool, cloudy, wet conditions July 30 and 31 were conducive for spread. Michigan State University Extension suggests that protection should be applied to all vine crops at this time. Protection should also be applied for powdery mildew since recent heavy dews will encourage infection.
Mite infestations have been found on watermelon. This is not surprising given the generally dry conditions we have experienced. Early infestations will be spotty. Look for yellowing areas in your fields and turn the leaf over since mites will generally be on the underside. We are reaching the end of the period when squash vine borer should be a concern, but squash bugs should be making an appearance soon.
Bacterial diseases have been found in some tomato fields. These will spread during times of cool, windy, wet weather. Grasshopper damage has also been noted in peppers (see photo). Grasshoppers may or may not be present, but their feeding pattern involves removing irregular sections of the leaf or entire leaves if the leaves are young and small. You may also see frass. Weather conditions have been favorable for development of blossom end rot. Blossom end rot is a calcium deficiency influenced by genetics, soil moisture, weather conditions and available soil calcium. It is worse with high light and favorable temperatures, which cause plants and fruit to grow quickly, thus limiting the calcium. Growers should provide adequate moisture so calcium can move into the plant.
Early potato harvest for chipping will begin this week.
There are still few signs of virus symptoms on any crop.