Grand Rapids, Mich., area small fruit regional report – April 30, 2013

Cold and wet conditions during the past weeks are bringing challenges to blueberry growers to manage early season diseases and weed problems in a timely manner.

As of April 30, the conditions of small fruit crops in the Grand Rapids, Mich., region are advancing rapidly toward completing the early stages of development. So far, there has been a considerable improvement on the regional weather conditions that has favored rapid development of our main berry crops. Currently, the region is experiencing a period of warm weather with only scattered rain showers in contrast with the past weeks torrential rains and wet snow periods. Despite those improvements, a large portion of fields are still partially flooded, making it difficult to initiate the normal crop management practices such as the seasonal applications of fungicides, post-emergence herbicides and nutrients.

For blueberries, warm weather conditions from the past week advanced the development of all varieties, especially in blueberry fields south of Ottawa County. Currently, blueberry plant growth has advanced from bud break to the green tip stage in early season varieties. In fields with good irrigation and nutrient management, flower buds are large and well-developed, which indicate a potential large blueberry crop.

However, fields that had problems during the past two years with frost damage and drought may have a moderated crop since they may require more intensive pruning to remove dead or damaged canes. At this time it is easy to distinguish these canes because they look bleached, weak and with few buds or no buds at all. Leaving those shoots on the plant will interfere with the normal development of new canes that will replace damaged or dead canes. Since they are still connected to the crown of the plant they will be extracting nutrients that will be lost because no commercial crop will be produced on them.

Regarding pest and management problems in blueberries, mummy berry mushrooms are out and growers need to start the fungicide applications to prevent shoot strike infections and problems at harvest time with infected fruits. Most effective fungicides for mummy berry control are Indar, Orbit and Quash. For Indar applications to be most effective, the volume of water used should be at least 20 gallons per acre for ground application and 10 gallons for aerial application. Mummy berry control increases when the application is conducted within 24 hours of a frost event.

Quash, on the other hand, should not be applied with adjuvants and the grower or applicator must have the supplemental label at hand. For more mummy berry treatment options, please consult the 2013 Michigan Fruit Management Guide (Michigan State University Extension Bulletin E-154).

Another consequence of the intense rains that occurred over the past weeks is the problem with weeds. Growers need to take care of grass and annual weeds as soon as the conditions may allow entering the fields. If no pre-emergent herbicides were applied during the fall, it is necessary to apply an herbicide that can control both annual grasses and weeds before and after they emerged. One herbicide that meets these requirements could be Chateau.

Chateau controls many broadleaf and grass weeds, including chickweeds, dandelion, common groundsel, lambsquarters, eastern black nightshade, several pigweeds, ragweed and most annual grasses. Chateau also provides some burn-down of small weeds if combined with surfactant or crop oil concentrate (COC). Apply 6 to 12 ounces of product per acre to bushes that have been in the field for two years or more. For more options, please consult the 2013 Michigan Fruit Management Guide or MSU Extension’s tip sheet, “Blueberry Weed Control: Late Spring and Summer Options.”

For the other crops like strawberries and raspberries, the conditions are still in early stages of development. For example, new leaves in strawberries are emerging from the crown, but no flower trusses are visible. Since the risk of spring frosts is still present, growers must keep the frost protection and irrigation system ready for use in case of an expected freeze or frost event. On the other hand, in summer raspberries, new growth is coming from the ground and is developing rapidly. So far, no substantial problems are affecting those fields.

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