Strawberry and Raspberry Pest Management in Wisconsin

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32 Raspberry Disease Management Cane diseases, Verticillium wilt, and gray mold are the more important fungal diseases that affect raspberries in Wisconsin. Viral diseases, such as crumbly berry and mosaic, are apparently widespread in Wisconsin and may be the limiting factor for raspberry production in older plantings. Accurate diagnosis of a disease problem is essential before effective disease management can be implemented. Bear in mind that several important diseases of raspberry, including Verticillium wilt and viral diseases, cannot be controlled with fungicides. While certain cultivars of raspberry are notably susceptible to some diseases, cultivars that are highly resistant to the most important diseases in Wisconsin have not been identified. These facts underscore the importance of sanitation and cultural practices in managing diseases of raspberry. FUNGICIDE UPDATE In recent years there have been several changes in fungicides registered on raspberry and other brambles. Always read labels carefully to be certain that the product formulation is registered on the type of bramble or “caneberry” crop you wish to treat. Myclobutanil fungicide previously was sold for use on fruit crops under the trade name “Nova” and now is sold under the trade name “Rally.” The formulation is identical, and use recommendations on strawberry and raspberry, including rates and timing, have not changed. Growers may continue to use existing stocks of Nova according to that product’s label. Myclobutanil is especially effective in controlling rust diseases of brambles. Azoxystrobin fungicide previously was marketed to strawberry and raspberry growers under the trade name “Quadris” and now is marketed as “Abound.” Existing stocks of Quadris may be used on strawberry and raspberry only if you hold the original label listing these crops. Quadris is still labeled and marketed for use on many vegetable crops, but newly purchased Quadris may not be used on strawberries or raspberries. Abound is effective in controlling several diseases of raspberry, including anthracnose, spur blight, leaf spot, rusts, and powdery mildew. Abound and Quadris both are highly toxic to certain apple varieties, especially McIntosh and related varieties. Even a small amount of Abound or Quadris, such as spray drift or spray tank residue, is toxic to apple leaves and fruit. Therefore, these products are not recommended for berry growers who also grow apples. Orbit (propiconazole) is an older fungicide that only recently has been labeled for use on strawberry and raspberry. Propimax is another brand of propiconazole; it is registered on raspberry and other “caneberries” and “bushberries,” but not on strawberry. Orbit and Propimax are in the same class of fungicides as myclobutanil (Nova, Rally). On raspberry these fungicides are labeled for control of Septoria leaf spot, rusts, and powdery mildew. Various phosphorous acid products (also called phosphites or phosphonates) are registered on fruit crops. These are related to fosetyl-aluminum (Aliette), which has been used to control Phytophthora pathogens of small fruits for years. On raspberry, these products are used to control Phytophthora root rot. Because these
products are taken up through leaves and then transported to roots, they require thorough wetting of foliage. Several highly effective fungicides can manage the most important diseases in Wisconsin. Many newer products are considered “reducedrisk” because of their relatively low toxicity to humans and wildlife. However, many are also at great risk of having fungal pathogens develop resistance to them. Most product labels include recommendations for resistance management, including limits on the number of sprays per season or number of consecutive sprays of a “resistance group.” Most labels specify a resistance group number, based on a fungicide’s mode of action and chemical class. For the purpose of resistance management, fungicides in the same resistance group are considered identical. For example, Abound is in resistance group 11. One component of Pristine is also a group 11 fungicide. Therefore, Abound and Pristine are equivalent in a resistance management program. PREPLANT SOIL FUMIGATION Soil fumigation reduces the populations of soilborne fungi and nematodes and should be considered when establishing a planting if fruit or vegetable crops have previously been grown on the site. Most fumigants are restricted-use pesticides and may be applied only by certified applicators. FUNGICIDE RESISTANCE Many fungicides are specific in the way they kill fungi. This specific nature is good in that non-target, beneficial microorganisms are often spared, but bad in that disease-causing fungi can readily develop resistance to the fungicide. To prevent the development of fungicideresistant pathogens, never use Elevate, Rovral, Nova, Cabrio, or Pristine exclusively in a season-long program. Also, try to reduce the total number of fungicide applications . See product labels for specific recommendations on resistance management. DISEASE NOTES Gray mold (Botrytis fruit rot) Gray mold, caused by the fungus Botrytis cinerea, can cause losses in the field and limits the postharvest storage life of berries to just a few days. Cultural practices that promote rapid drying of plants will help prevent gray mold. The most critical time for fungicide application is during bloom, since the fungus can infect flowers and then remain “dormant” until fruit ripen. Make the first application when about 5–10% of the flowers are open and a second application during full bloom. If you have different cultivars that bloom at different times, treat them separately. Cane diseases Cane blight, spur blight, and anthracnose are caused by fungi that overwinter on dead canes. Therefore, removing canes from the site reduces the inoculum available for the following year. If this is impractical, then chopping canes with a flail mower will accelerate their decomposition and prevent the fungi from overwintering. Cultural practices that promote air circulation and drying of foliage, such as narrowing rows and maintaining proper cane density within rows, will also deter these diseases. Liquid lime sulfur applied when buds show 1/4–1/2 inch green will kill inoculum that has overwintered. If applied later, however, lime sulfur can damage the plants. Fire blight Fire blight on raspberry is caused by the same bacterial species (Erwinia amylovora) that causes fire blight on apple and pear. However, the strains that infect apple and pear will not infect raspberry and vice versa. Infected canes become blackened as though scorched by fire and 33
Page 1 and 2: A1934 Strawberry & Raspberry Pest M
Page 3 and 4: INTEGRATED PEST MANAGEMENT FEDERAL
Page 5 and 6: PESTICIDES AND COMMUNITY RIGHT-TO-K
Page 7 and 8: Table 2. Examples of pesticides wit
Page 9 and 10: Table 3. Toxicity categories of pes
Page 11 and 12: Reportable spills involving SARA su
Page 13 and 14: Planter granular applicators can be
Page 15 and 16: Please note that this recycling pro
Page 17 and 18: Strawberry Disease Management Read
Page 19 and 20: Table 5. Disease resistance ratings
Page 21 and 22: Strawberry Insect Management INSECT
Page 23 and 24: Table 6. Spray schedule for strawbe
Page 25 and 26: Table 6. Spray schedule for strawbe
Page 27 and 28: Strawberry Weed Management A succes
Page 29 and 30: label for specific instructions on
Page 31 and 32: Table 8. Weed management for strawb
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Page 37 and 38: Raspberry Insect Management Several
Page 39 and 40: Table 9. Spray schedule for raspber
Page 41 and 42: Raspberry Weed Management Effective
Page 43 and 44: Table 10. Weed management for raspb
Page 45: SPRAY RECORD SHEET Date applied Mat

Strawberry and Raspberry Pest Management in Wisconsin

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