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It is mid-October, and strawberry planting season is upon us. Most strawberry growers in our region use the annual hill plasticulture system and plant short day or spring-bearing strawberry varieties. These strawberry plants will begin to grow during the warmer parts of the fall and become dormant during the winter months. When weather conditions become favorable in the spring, strawberries will begin to bloom and set fruit. From planting to harvest, strawberries have a long growing season, remaining in the field for a considerable duration – as long as 8 months. Consequently, there are plenty of opportunities for diseases to develop. Timely, effective disease control methods are important and could make the difference between a profitable one and a disastrous one.

Last year, anthracnose created problems in strawberry plantings in Alabama and all over the Southeast. It is an economically important disease of strawberries associated with fungi of the genus Colletotrichum. Depending on the species of Colletotrichum, the disease can affect all parts of the plant (Fig. 1 and 2). Anthracnose fruit rot is caused by C. acutatum, while anthracnose crown rot is caused by C. gloeosporioides and C. fragariae. Conditions ranged from manageable to near crop failure. Growers who followed a regular spray program were the most successful.

Figure 1. Anthracnose fruit rot caused by Colletotrichum spp. Photos by Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org

Fig. 2. Anthracnose crown rot caused by Colletotrichum spp. Photo by Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org

 

 

Managing disease in strawberry

Following an effective spray and sanitation program can help to manage disease in strawberries. Here are some tips to follow to prevent or minimize damage caused by disease.

  1. Begin with healthy plants. Acquire plants from a reputable nursery. Often, diseases such as anthracnose will be present on plants at the nursery. Be sure that your plants are certified disease-free.
  2. Plant resistant cultivars if possible. A few cultivars have demonstrated resistance to anthracnose fruit rot such as ‘Sweet Charlie’ and ‘Bish’. Regardless of a variety’s resistance to a particular disease, try a small planting before committing significant acreage to a new variety.
  3. Monitor fields for disease. Scout the field for infected plants especially when conditions are warm and wet. If there are localized areas of infection or ‘hot spots’, remove and destroy (burn) all infected plants in the area as well as any plants within a 5 to 10 ft. radius of the infected area. Harvest all known areas of infection last to minimize the spread of the disease. Eliminate or minimize the use of overhead irrigation.
  4. Early and regular sprays. Begin your spray program early and apply sprays as recommended being careful to follow all pesticide labels. The Southeastern Regional Strawberry Integrated Pest Management Guide for Plasticulture Production, developed by experts at the Sothern Region Small Fruit Consortium (SRSFC) can be found online.  The SRSFC is a multi-state alliance of small fruit growers, fruit industry leaders and service organizations that partner with and serve small fruit growers, agricultural Extension programs and agricultural research stations to develop and strengthen small fruit production in the region.
  5. Use sanitation. Reduce the population of disease-causing fungi by removing infected leaves and fruit.
  6. Use crop rotation. Placing strawberries in a rotation with other crops for 2 to 3 years will help to manage disease generally. However, anthracnose of strawberry is not known to remain in the field to infect new strawberry plants.
  7. Consider using a pre-plant dip. As mentioned previously, anthracnose created a significant challenge to growers during our recent strawberry season. Growers that had a profitable season began their spray programs early and applied sprays regularly. Another component to add to your disease protection arsenal is the use of dips. Certain fungicides, such as Switch, can be used as dips and have been shown to reduce the incidence of anthracnose and botrytis (gray mold) (Fig. 3). Prior to planting, plants should be submerged in the dip for at least two minutes. For more information on the use of Switch as a dip to control foliar diseases, see Table 1, which is an excerpt from the label.

 

Figure 3. Symptoms of gray mold (Botrytis cinerea). Photo by Don Ferrin, Louisiana State University Agricultural Center, Bugwood.org

 

Table 1. Use of Switch fungicide as a dip to control foliar disease in strawberry

CropDiseaseProduct Rate oz./acreRemarks
Strawberry and Berry, Low Growing Subgroup 13-07G (except Cranberry)* and cultivars and/or hybrids of theseRoot and crown anthracnose at planting (Colletotrichum spp.)5-8 oz per 100 gal waterApply as a preplant dip to strawberry roots and crowns at the rate of 5 to 8 oz per 100 gallons of water for suppression of root and crown rot caused by anthracnose. Wash transplants to remove excess soil prior to dipping. This helps to remove adhering spores from the external plant parts. Completely immerse planting stock in dip solution. Dip or expose plants for a minimum of 2 to 5 minutes. DO NOT reuse solution. Dispose of dip solution according to local regulations. Plant treated plants as quickly as possible. For continued anthracnose control, follow with foliar applications of beginning 2-3 weeks after transplant.

 

Foliar disease in strawberry can be a challenge to manage. Infected plants can harbor Anthracnose without showing symptoms. Do not wait unit symptoms appear to manage Anthracnose. Following the disease management program described in the SRFC strawberry IPM guide will help to ensure a successful strawberry season.

 

 

 

 

 

 

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