Impact of heat, drought and related problems on Michigan’s blueberry and raspberry harvest

Hot and dry weather conditions occurring in Michigan during the 2012 season are not conducive for a “normal” small fruit harvest.

Blueberry and raspberry growers are having problems with fruit ripening too fast, birds and insect pest problems associated with the appearance of the spotted wing Drosophila. Drought problems are more severe for fruit crops lacking supplementary irrigation. In blueberries, for example, 25 percent of the blueberry harvested area is non-irrigated according to the last Michigan Fruit Inventory (2006-2007). Those fields are the most affected by the prevailing weather conditions.

Currently, all crops including fruits are suffering due to the severe drought. For raspberry growers with summer varieties, the prevailing weather conditions are causing problems because the fruit is ripening very rapidly and in a very short period of time. Instead of having the raspberry crop over a several-week period, it has been concentrated in a period of a few days. This causes problems if not enough buyers are available at the time of harvest. Raspberries are a delicate fruit with a very short shelf life. Fresh, harvested raspberries need to be immediately refrigerated to maintain their quality. Thus, the grower requires having a refrigeration unit available during harvest time to prevent substantial lost.

For organic growers and growers that use a limited amount of insecticides and fungicides, this season is very problematic. Under these conditions, fruit rots are causing significant losses after harvest. Harvested raspberries last no more than a day if fungicides have not been applied to them during the pre-harvest or if they are left unrefrigerated.

On the other hand, despite the drought and intense heat, blueberries are doing much better than the other fruit crops. Blueberries were able to survive the freeze and frost events that occurred at springtime with a very decent crop in relationship to Michigan’s other major fruit crops: apples, cherries and peaches. The current heat and drought wave may have a negative impact in the final crops results. Currently, the blueberry harvest is in progress with fruit of good quality in fields that have been on top of the drought situation. However, in fields without irrigation, the situation is not very good.

Early in the spring right after the last frosts, the 2012 blueberry crop was estimated to be around 81 million pounds (see the MFFPA Fruit Crop Guesstimate). However, right now after this severe drought, crop estimates are going down since a substantial portion of the fruit crop in non-irrigated fields (25 percent of the fields are non-irrigated) is being lost or at risk if no rain is available soon. Currently, fields that were affected by spring frost and, more recently, by drought conditions are showing small fruit that is unevenly ripening. We find fruit cluster with a mix of ready-to-harvest fruits and a large proportion of small, unripen fruits. These conditions make it difficult for both hand-pick and mechanical harvest.

Well-irrigated blueberry fields are having a good crop with fruit of good quality. In those fields, fruit ripening is occurring very fast and the harvest is being concentrated in a short period of time. Most early and mid-season varieties are already at the pick (north of Ottawa County) or close to finishing the hand-harvest (especially in southwest Michigan) with many fields already machine-harvesting what remains of the crop. In southern counties Allegan and Van Buren, because of the drought situation and hot weather growers may start hand-harvesting some Elliott fields that are already showing some fruit that is ripening well in advance.

One major problem affecting all berry crops is the presence of large flocks of birds. The lack of other fruit crops in most of the state is causing them to concentrate their attention on the only available food – small fruit crops. Blueberry and raspberry growers are being forced to “share” the crop with birds. There are few options to control birds and most growers are powerless to control this problem.

Regarding insect problems, so far the spotted wing Drosophila has been found in both blueberries and raspberries. Growers need to be aware of its presence in their fields. Monitoring is very important to prevent fruit infestations. We would like to remind growers that those insecticide treatments against Japanese beetles or blueberry maggots will not provide full protection against spotted wing Drosophila. If the pest is present, more frequent insecticide applications than those applied against these other pests are required to maintain a good spotted wing Drosophila control.

For blueberry and raspberry growers, information on monitoring, identification and control of the spotted wing drosophila is available at the MSU IPM Spotted Wing Drosophila website. Growers may also get assistance by calling MSU Extension small fruit educator .(JavaScript must be enabled to view this email address) at 616-260-0671.

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