West Central Michigan small fruit regional report – June 17, 2014
Strawberries are in full harvest with minimal issues, but summer heat and low relative humidity may create sun scald and fruit rot infections. Fruit ripening increases potential for insect pests, and spotted wing Drosophila should be monitored.
So far, the small fruit crop season continues progressing without major problems. Daily temperatures have remained in the upper 70s and for the past seven days the average maximum temperature has been 78 degrees Fahrenheit and the minimum 53 F. Current growing degree day (GDD) accumulation is 1,062 base 42 F and 620 base 50 F. In general, the climate has been dry, prompting growers to supplement blueberry and strawberry fields with irrigation. However, we had some scattered rain showers that, in some areas, reached 2 inches in one single event.
Strawberry harvest continued in West Central Michigan with little problems. Strawberry yield is good, but some growers consider that the subzero temperatures at the end of the winter had considerable effect of the size of the crop. At this time, there are some problems related to sap beetles, fruit rots and sun scald due to the prevailing high temperatures and low relative humidity. Growers need to pay attention to the control of sap beetles because they may be a serious problem if left unattended.
Strawberry sap beetles usually show up when harvest is beginning. The best management for this pest is cultural, by sanitation and timely harvest. Sanitation means removing damaged or overripe berries. Picking plants thoroughly and regularly can help to manage this pest. Celeste Welty from Ohio State University Extension recommends mechanical control by placing trap buckets of over-ripe fruit at the field edge, which draws the sap beetles away from the main part of the field. For chemical control, the recommendation is to apply a short residue insecticide such as Brigade. Brigade has a zero-day pre-harvest interval, but a re-entry interval of 12 hours. For more insecticide options and doses, please consult the 2014 Michigan Fruit Management Guide (E-154).
Blueberries on the other hand are in the “green fruit” stage with a rapid increase in size and, at this time, in some fields in Allegan County, early varieties are sizing very well and we may expect the first harvest for the second week of July. Fields that were affected by winter temperatures are improving and in some cases management is making the difference. In some fields, there has been a development of secondary leaf buds providing some foliage that looks small, but it may help to bring the fruit development to completion.
Not all varieties are showing the same level of damage. In some areas, the most affected varieties are Elliott and Jersey. Other varieties like Duke and Bluecrop sustained little winter damage and the crop looks normal. In general, the West Central Michigan blueberry harvest may be 20-30 percent smaller than the year before. That is consistent with our early season evaluation that showed 20-30 percent average flower bud damage, depending on the variety, location and nutritional stage of the plant. For more information, see “2014 winter and road salt damage to blueberries in West Michigan” from Michigan State University Extension.
Regarding spotted wing Drosophila (SWD), we started its monitoring with the new synthetic lure which has replaced the mix of yeast and sugar used as an attractant for the last two years. At this moment in West Central Michigan, we have deployed SWD traps in strawberry fields in Ionia and Ottawa counties. Traps were deployed the past week. So far, no SWD have been trapped in any of those places.