Weather and pest problems plagued Michigan’s blueberries in 2012

The 2012 blueberry season has been plagued with problems like no other in many years. Weather, pests and labor problems have seriously challenged Michigan’s blueberry industry, however, there are lessons we can learn from the situation.

Weather events are phenomena that are impossible to predict or control. The only thing growers and researchers can do about these is to develop and implement measures and technologies that mitigate their impact. Early in the season, spring frosts caused major problem for growers that had no frost protection plan or lacked irrigation in their fields, or their irrigation equipment was deficient and unable to properly protect the crop. Because of the climate change phenomenon, circumstances as the ones we are experiencing during 2102 will occur again soon or later. Growers need to be aware that the main driving force of agriculture is climate. For blueberry production, spring frost and summer droughts are critical factors that limit the production and productivity of Michigan’s blueberry industry.

In Michigan, overhead irrigation is the most common method to irrigate and protect blueberries from frost damage. This year, right in the middle of the spring frost season, we found that overhead irrigation systems used for frost protection did not always accomplish the objective of protecting the crop they are supposed to protect. A lack of uniformity of the irrigation system was one problem we found by driving through fields early in the morning when the frost was in progress and the irrigation equipment was functioning. During the summer, the same lack of uniformity caused fields under irrigation to have large numbers of blueberry bushes with drought symptoms at the edges and inside the field, especially in fields located in light soils.

To do a uniformity check, see the MSU Extension article Conducting a sprinkler irrigation uniformity evaluation in your nursery. A take-home message resulting from this experience is that in the future for sustainable blueberry production, a properly designed irrigation system is essential. There is no future for an economically viable blueberry production system without the necessary investment in irrigation and frost protection.

As a direct consequence of climate change, regions like Michigan that had a very predictable weather patterns and well defined seasons start having sudden weather changes affecting the phenology of plants and insects. Erik E. Stange from the Norwegian Institute for Nature Research indicated that major impacts for insects are an improvement on the conditions for survival, reproduction and migration. Warmer climate will increase the longevity of individuals, their reproduction rate, and will affect their interaction with other species in their ecosystem, including natural enemy populations (see Climate Change Impacts: Insects for more information).

In similar manner, John T. Trumble and Casey D. Butler from University of California Riverside indicated that with a rise in temperatures, many insects will alter how much they eat in response to changing plant nutrition. Also, we can expect increased problems with many pest insects as they develop more rapidly in response to rising temperatures. They advise that if we hope to maintain sustainable agro-ecosystems, we need to begin preparing now for the challenges of a changing environment (see Climate change will exacerbate California’s insect pest problems for more information).

We are already seeing this phenomenon with the appearance of the spotted wing Drosophila (SWD). During the current season and as a consequence of the mild winter and early spring, SWD showed up in our detection system one month earlier than in 2011. Likewise, the dispersal and the size of the populations observed in small fruit fields are considerably bigger than in 2011. In 2010 when we started this monitoring, we found it mainly in blackberries and raspberries with a few blueberry sites with high infestations.

Currently, SWD has been found in large numbers in all small fruit crops, including strawberries. To make matters worse, high summer temperatures are not very conducive for effective pest control as pesticides are rapidly degraded by high environmental temperatures. Thus, in 2012, growers are spraying more often to keep in check the treatment of SWD at harvest time. We are learning from this experience that there is a need for retooling our integrated pest management (IPM) programs to accommodate SWD management and control. However, modifying our IPM for SWD requires extensive training of growers andIPM practitioners. Currently, insecticides used against SWD are applied on a calendar basis rather than on an IPM monitoring-based program. This will disrupt current IPM programs already established in Michigan’s blueberry fields.

The MSU Extension small fruit program is ready to provide growers with technical assistance to face the challenges posed by climate change by helping growers with training and advice to make the necessary adjustment to their crop management systems. For assistance with small fruit management problems, please visit our Michigan Blueberry Facts website. For spotted wing Drosophila weekly updates, please visit the MSU IPM Spotted Wing Drosophila website or contact Carlos García.

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