West central Michigan small fruit update – Aug. 15, 2017
Blueberry harvest is quickly moving along, with southern counties harvesting mainly late-season varieties. Since spotted wing Drosophila numbers are increasing, pay attention to management recommendations.
For the past two weeks, weather conditions in west central Michigan were dominated by moderate temperatures and scattered rain showers. These allowed for better control of insect pests and fruit rot diseases prevalent during the blueberry and fall raspberry harvest. Minimum temperatures during the past week averaged 56 degrees Fahrenheit and the daily maximum averaged 78 F. During the same period, rain showers left an accumulation of 0.51 inch of rain.
Fall raspberry harvest is in progress with fruit of good quality and flavor. Weather conditions are helping in preventing outbreaks of fruit rots and pollination is excellent. Although spotted wing Drosophila (SWD) is present in all fields, growers that maintain a rigorous pest control and practice removing ripe fruit on a daily basis are getting the upper hand against SWD. Berry growers in Ionia, Kent and Ottawa counties are reporting good SWD control.
On the other hand, blueberries harvested for fresh are clean and of very good flavor. There are some occasional reports of Alternaria and anthracnose fruit rot. However, these diseases do not represent a significant problem.
The insect pest problem continues to be the main concern for blueberry growers. Although reports of rejected or downgraded fruit remains very low this season, the number of SWD caught in traps continues increasing, putting late-season varieties at risk that are harvested at his time.
Current weather conditions have been in our favor to maintain good SWD control with recommended insecticides. With the exception of the last week on July when the SWD outbreak was aided by high temperatures and high relative humidity, moderate temperatures are helping to maintain the effectiveness of all recommended insecticides.
However, SWD trapping continues being a problem in many fields. Traps made from small, plastic jars (less than 8 ounces) are not as effective as the Michigan State University Extension recommended traps made of a 32-ounce plastic container loaded with a commercial lure. Side-by-side, more flies are trapped in recommended traps than in these other small traps. The lack of efficiency of these traps is leading growers to delay applications and have control problems. Fix these problem to improve SWD control and prevent extemporaneous applications. Those applications do not prevent larval infestations and only increase pest control expenses.