Commercial Crop Production Small Fruits - Strawberries

Transcription

1 Integrated Strawberry anagement Strawberries are among the most challenging horticultural crops to grow in the South due to high levels of soilborne pathogens. Chemical use, from pre-plant to harvest, is a critical component in maintaining crop yield and producing high-quality fruit. Traditionally, successful disease management in strawberries has relied on the establishment of a clean crop planted into methyl bromide fumigated soil. With the phaseout of methyl bromide, however, the use of alternative and more sustainable management strategies are necessary. Comprehensive reduced-risk strategies for managing strawberry pests are available from the University of California IP Online statewide program at Anthracnose Crown Rot (Colletotrichum spp.) Symptoms: Plants wilt suddenly and die during warm weather. Crowns have a reddish discoloration extending into the center. Black lesions occur on leaf petioles or runners. development is inhibited by cool weather. Source of Inoculum: The fungus survives the winter on infected plant parts or is introduced on infected planting material. Fungal spores are spread primarily by rain splashing and winddriven rain. anagement: Use disease-free transplants. Dip plants in a fungicide prior to planting. Rogue out infected plants and treat surrounding plants with fungicides. Azoxystrobin Abound Heritage + fenhexamid Captevate azoxystrobin + Phytophthora Crown Rot (Phytophthora spp.) Symptoms: Youngest leaves often wilt first followed by the collapse of the entire plant. Crowns exhibit extensive brown discoloration that extends from the crown downward or from an infected stolon. Source of Inoculum: Oospores that survive in the soil or on infected Aluminum tris Aliette Legion efenoxam Ridomil etalaxyl etastar Phosphite

2 transplants. Spreads primarily in water. anagement: Use disease-free transplants, improve drainage and avoid low spots. Dip transplants in suitable fungicide prior to planting. Rogue out infected plants and treat surrounding plants with fungicide. Fosphite Gray old (Botrytis cinerea) Symptoms: This fungus attacks flowers, flower parts, fruit and leaves. On the fruit, this disease causes a rot that is at first light brown and soft (not leaky ). As the berry rots, it becomes covered with a grayish, powdery growth, and in the final stages of rot, it becomes tough and firm in texture. Source of Inoculum: The fungus survives in the decaying tissues of strawberries and many other plants. Fungal spores are wind-dispersed. anagement: Control leaf diseases and remove dead leaves that can furnish a site for the fungus to develop. Remove infected fruit from the field. Spray with fungicides. Azoxystrobin Abound Heritage Captec + fenhexamid Captevate Fenhexamide Elevate Trifloxystrobin Flint Pyrimethanil Scala cyprodinil + fludioxonil Switch Thiram

3 Angular Leaf Spot (Xanthomonas fragariae) Symptoms: First visible as tiny, watersoaked spots on the lower leaf surface that enlarge into angular lesions delimited by leaf veins. Lesions appear translucent when held up to the light. Bacterial ooze may be found on lesions on lower leaf surfaces. Source of Inoculum: The bacterium survives in infected leaf debris or is introduced on infected planting material. Bacterial cells are spread primarily by rain splashing and winddriven rain. develops most under cool, wet conditions. anagement: Use disease-free transplants. Spray with copper fungicides. Copper sulfate Cuprofix + + Powdery ildew (Sphaerotheca macularis f. sp. fragariae) Symptoms: A white powdery growth is present on the undersurface of infected leaves and on fruit. Infected leaves have a tendency to roll up. Source of Inoculum: The fungus persists from year to year on infected strawberries and other wild hosts. Usually a problem in the spring and early summer months. anagement: any varieties are resistant to this disease. Spray with fungicides. Azoxystrobin Abound + fenhexamid Captevate Trifloxystrobin Flint Sulfur icrothiol yclobutanil Rally + +

4 Azoxystrobin + Triflumizole Procure Quinoxyfen Quintec + + Leaf Spot (False rust or bird s-eye spot) (ycosphaerella fragariae) Symptoms: The spots are at first less that 1/8 inch in diameter and purplishred. Spots enlarge to about 3/16 inch. They have white or gray centers with purplish borders. Source of Inoculum: The fungus survives from year to year on infected plant parts. anagement: Spray with fungicides. Captec yclobutanil Rally Azoxystrobin + Dodine Syllit + captan +

5 Leaf Blight (Phomopsis obscurans) Symptoms: First appears as large, circular, reddish-purple spots that become zonate with age (i.e., they have a dark brown center surrounded by a lighter brown area with a purplish border). ature spots may be circular, oval or V-shaped. Source of Inoculum: The fungus lives from year to year primarily on infected plant tissue. anagement: Use disease-free transplants. Spray with fungicides. Captec yclobutanil Rally Azoxystrobin + Dodine Syllit + captan + Leaf Blotch (Gnomonia spp.) Symptoms: First appears as purplish to brownish blotches on young leaves. Later appears as large, light brown spots on older leaves. ay affect fruit as well. Source of Inoculum: The fungus lives from year to year primarily on infected plant tissue. anagement: Spray with fungicides. Captec

6 yclobutanil Rally Azoxystrobin + Dodine Syllit + captan + Leaf Scorch (Diplocarpon earlianum) Symptoms: The disease first appears on upper leaf surfaces as small purplish spots that enlarge rapidly into irregular purplish blotches from 1/16 inch to 3/16 inch in diameter. The spots may become numerous and coalesce. In severe cases, the edges of the leaflets curl upward and the tissue dies, giving the plant a scorched appearance. Source of Inoculum: The fungus survives from year to year on infected leaves. anagement: Use disease-free transplants. Rotate strawberry fields, if possible. Spray with fungicides. Captec yclobutanil Rally Azoxystrobin +

7 Nematode s Dodine Syllit + captan + Root-Knot Nematodes (eloidogyne spp.) Summer Dwarf or Bud Nematode (Aphelenchoides besseyi) Symptoms: Affected plants are stunted, unthrifty, unproductive and often pale green. Galls or knots on the roots are rather small. Numerous secondary roots may develop at the small swellings. Frequently, blackened, rotten roots are associated with root-knot problems. Source of Inoculum: Root-knot nematodes live from year to year in the soil and on the roots of strawberry plants and many weeds. Root-knot nematodes are more severe in light soil types. anagement: Fumigate plant bed soil and field soil. See table on Nematode Control in Fruit Crops. Symptoms: Affected plants are severely stunted during the summer and early fall. Older leaflets usually are darker green with a greasy appearance. Young leaflets are reduced in size, usually crinkled and somewhat elongated, with shorter petioles. argins of leaflets may curl upward in the young leaflets and downward in the older leaflets. Source of Inoculum: Bud nematodes live from year to year on infected daughter plants and in the soil. anagement: Fumigate fields where the disease has occurred. Obtain disease-free plants. There is no satisfactory treatment to eradicate these nematodes from infected plants. 1 References to commercial or trade names are made with the understanding that no discrimination is intended nor is endorsement of a particular product by LSU or the LSU AgCenter implied. ratings are on a 1-5 scale where: + is the most effective and + is the least effective. Ratings are from the 7 Southeast Regional Strawberry Integrated anagement Guide of the Southern Region Small Fruit Consortium ( Data are not available for fungicides with no efficacy rating.

8 Table. Seasonal fungicide spray schedule for strawberries Season Pesticide Application Timing 1 s Pre-planting Post-planting until pre-bloom Post-planting fungicide dip Early post-planting Warm periods following frost Colletotrichum (anthracnose) crown rot Phytophthora crown rot Colletotrichum (anthracnose) crown rot Phytophthora crown rot Powdery mildew Botrytis crown rot Bloom until harvest New growth Every 7 to 1 days or according to label Leaf spots (bacterial and fungal) Phytophthora crown rot Powdery mildew Colletotrichum (anthracnose) crown rot Gray mold Leaf spots (bacterial and fungal) Phytophthora crown rot Powdery mildew 1 For more information on seasonal fungicide spray schedules refer to the 7 Southeast Regional Strawberry Integrated anagement Guide of the Southern Region Small Fruit Consortiumhttp:// Bare-root strawberry plants may be dipped in a fungicide suspension prior to planting to provide early season control of root and crown rot diseases. Prior to dipping, the plants should be washed with potable water to remove adhering soil. The entire plant should be treated according to the label. Plants should be as soon as possible.

9 Table 3. Recommended pesticides, rates and pesticide use restrictions for strawberries The symbol OG indicates a pesticide that has been listed by the Organic aterials Review Institute (ORI) as approved for use in organic production. Product Choices 1 and Product ode of Rate 3,5 PHI 4 aximum Use Action Group aluminum tris (O-ethyl phosphonate) Aliette Legion 8WDG.5 lb 8-5 lb lb 3 lb azoxystrobin Abound fl oz 61.5 fl oz azoxystrobin + 3,11 14 fl oz 56 fl oz boscalid + 7, oz 115 oz 5W Captec 4L 3-6 lb qt 48 lb 4 qt captan + fenhexamid Captevate, lb 1 lb copper hydroxide Champ WG OG 3-3 lb lb lb lb 7.3 lb 3.4 lb copper hydroxide + copper oxychloride Badge X OG lb 6 8. lb Cu copper sulfate Cuprofix Ultra 4 Disperss lb lb cuprous oxide Nordox -8 lb 1 cyprodinil + fludioxonil Switch 6.5WG 9, oz 56 oz Fenhexamid Elevate lb 9 6 lb Fluoxastrobin Aftershock fl oz 1.8 fl oz iprodione 4L AG 4F 1.5- pt 1.5- pt 1.5- pt app 1 app 1 app

10 Table 3. Recommended pesticides, rates and pesticide use restrictions for strawberries The symbol OG indicates a pesticide that has been listed by the Organic aterials Review Institute (ORI) as approved for use in organic production. Product Choices 1 and Product ode of Rate 3,5 PHI 4 aximum Use Action Group mefenoxam Ridomil Gold SL Ultra Flourish pt 1 pt lb a.i. 6 pt metalaxyl etastar 4 qt (per treated A) 13 myclobutanil Rally 4WSP oz 3 oz Penthiopyrad Fontelis fl oz 7 fl oz phosphite Fosphite Fungi-phite Helena Prophyt phorcephite Phostrol Rampart 41.8EC qt 1- qt -4 pt -4 qt.5-5 pt 1-3 qt 4 fl oz 4 fl oz 4 fl oz 6 app 6 app 16 fl oz 16 fl oz 16 fl oz oz 7 oz pyrimethanil Scala 9 18 fl oz 1 54 fl oz quinoxyfen Quintec fl oz 1 4 fl oz Sulfur 14 icrofine Sulfur OG icrothiol Disperss OG Yellow Jacket Dusting Sulfur Yellow Jacket Wettable Sulfur 3-5 lb 5-1 lb 1- lb 3-5 lb 4.5 FL fl oz 1 8 fl oz

11 Table 3. Recommended pesticides, rates and pesticide use restrictions for strawberries The symbol OG indicates a pesticide that has been listed by the Organic aterials Review Institute (ORI) as approved for use in organic production. Product Choices 1 and Product ode of Rate 3,5 PHI 4 aximum Use Action Group 85 WDG lb 1 3. lb trifloxystrobin Flint oz 19. oz triflumizole Procure 48SC fl oz 1 3 fl oz 1 Reference to commercial or trade names is made with the understanding that no discrimination is intended nor endorsement of a particular product by LSU or the LSU AgCenter is implied. ode of action groups are determined by the Fungicide Resistance Action Committee (FRAC). 3 Rates are the amount of formulation per acre unless otherwise indicated. Usually 1 gallons of water are required to give good coverage with boom sprayers. 4 Post-harvest interval (PHI) is the minimum number of days allowed between the last application and harvest. 5 All rates refer to foliar applications unless otherwise noted. Refer to label for other application rates and directions. 6 Do not use in a spray solution with a ph less than Do not apply to cvs. Clancy, Jewel, or L Amour. 8 Do not apply more than 3.75 lbs. product (3 lbs. AI) per acre per application in Livingston or Rapides parishes in order to protect endangered freshwater mollusks and their habitats. 9 When plastic mulch is used do not apply within 16 ft naturally vegetative or aquatic areas. 1 Do not apply after first fruiting flower. 11 Supplemental label (EPA Reg. No ). Expires arch Applications by ground (banded), drip, or overhead chemigation. 13 Apply in banded sprays or drip irrigation. 14 Do not apply when temperatures are expected to exceed 9 F for three or more days. Revised December 13 by Dr.. Lewis Ivey.