Fundamentals of Caneberry Production Workshop Understanding Pathogen Biology & Diversity ESTABLISHMENT CONSIDERATIONS OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Establishment Considerations Crown gall, nematodes, and viruses are best controlled through prevention or elimination prior to planting Crown gall is caused by soil-borne bacteria which result in tumorous growth on plant crowns and root systems Nematodes directly destroy roots and increase crown gall and root rot; dagger nematodes spread caneberry viruses Viruses reduce vigor, yield, fruit quality; cause plant death Martin et al. 2013 Martin et al. 2013 Martin et al. 2013 Martin et al. 2013 Many viral diseases affect caneberries including Blackberry Yellow Vein Disease (above) Understanding Pathogen Biology & Diversity ESTABLISHMENT CONSIDERATIONS OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Viruses and Crown Gall • Since viruses and crown gall can be introduced through propagation, clean planting stock is essential. • Tissue-cultured plants are more likely free of pathogens • Wounds are required for crown gall infection. Every effort should be made to avoid wounding roots and lower stems. • Once infected, plants cannot be cured of viruses. 1. Set out only disease-free plants. 2. Remove wild blackberries growing nearby that can harbor caneberry viruses 3. Rapidly remove symptomatic plants Understanding Pathogen Biology & Diversity ESTABLISHMENT CONSIDERATIONS OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Nematodes • Nematode control, especially of dagger nematode, is essential to prevent virus spread; even low levels of dagger nematodes are dangerous. • Prior to land prep, all potential sites should be sampled for root-knot, root-lesion, dagger and other nematodes. • Fumigation prior to planting is often recommended to reduce/prevent nematode issues. • Chemical controls include: Pic-Clor 60, Paladin, Vapam, Sectagon 42, K-PAM HL, and Telone II. Understanding Pathogen Biology & Diversity PHYTOPHTHORA ROOT ROT OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Phytophthora Root Rot • Reportedly caused by several Phytophthora spp. • Phytophthora spp. produce zoospores & spread via water • Disease often first seen in poorly drained areas of the field • Damage to roots leads to primocane collapse shortly after emergence in the spring as well as wilting and chlorosis of floricanes W. Wilcox https://ohioline.osu.edu/factsheet/plpath-fru-14 https://ohioline.osu.edu/factsheet/plpath-fru-14 Reddish brown root discoloration Cane collapse due to root rot Root rot affected plant (left) Understanding Pathogen Biology & Diversity PHYTOPHTHORA ROOT ROT OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Management • Cultural controls are critical since root rot is generally a problem of low, poorly-drained, excessively moist sites. Ensure adequate drainage prior to planting via site selection and/or proper bedding Avoid excessive irrigation • Chemical controls for include phosphonates (ProPhyt, K- Phite, etc.) and mefanoxam (Ridomil Gold). • Note that chemical control is not effective for reversing root rot damage on plants with severe symptoms SOUTHEASTERN CANEBERRY SEASONAL SPRAY SCHEDULE https://berrydealer.com/blackberries/ Example Seasonal Spray Schedule Delayed Shoots Bloom Petal Cover Preharvest Harvest After Dormant 6” long Fall Sprays harvest Anthracnose & Spur Blight Cane Blight Leaf Spots Rusts & Powdery Mildew Botrytis & Rosette Orange Cane Blotch Understanding Pathogen Biology & Diversity ANTHRACNOSE OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Anthracnose • Caused by the fungus Elisnoë necator • Disease is more serious on raspberry than blackberry • Reddish-purple spots appear on primocanes in the spring • Spots develop into sunken lesions as the disease progresses • Infection of leaves (purple spots) and fruit (small, mis- shapen) can also occur MyIPM App MyIPM App MyIPM App Early spots symptoms on primocanes Sunken lesions Understanding Pathogen Biology & Diversity ANTHRACNOSE OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Management • Cultural controls include: • Removal of old floricanes immediately after harvest • Promoting rapid drying of the canopy through the use of weed free strips, black plastic, and drip-tape irrigation • Avoiding overhead irrigation to prevent splash dispersal • Avoiding excessive nitrogen applications • Chemical controls include: • Application of lime sulfur in the late dormant period • In-season applications of additional fungicides (Abound, Quilt Xcel, Pristine, Cabrio, and Captan) Understanding Pathogen Biology & Diversity SPUR BLIGHT OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Spur Blight • Caused by the fungus Xenodidymella applanata (AKA Didymella applanata) • Generally more severe on raspberries than blackberries • Not widespread in southeastern US caneberries • Infections produce V-shaped lesions primocane leaves • Infections eventually spread from leaf margins, down the petioles, and then into the node Bugwood.org T. McCamant Mary Ann Hansen V-shaped lesions w/yellow margins Purple/dark brown lesions on primocanes Understanding Pathogen Biology & Diversity SPUR BLIGHT OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Management • Cultural controls include: • Removal of old floricanes immediately after harvest • Promoting rapid drying of the canopy through the use of weed free strips, black plastic, and drip-tape irrigation • Chemical controls include: • Application of lime sulfur prior to spring growth • In-season applications of additional fungicides (Abound, Quilt Xcel, Pristine, Cabrio, and Captan) Understanding Pathogen Biology & Diversity CANE BLIGHT OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Cane Blight • Caused by the fungus Leptosphaeria coniothyrium • Fungal spores (conidia) are spread by rainsplash and infect canes through wounds. • Lesions appear on primocanes in summer, fall, and winter. • Cane death results when lesions girdle the vascular tissue. MyIPM App MyIPM App MyIPM App Blighted canes often appear to be grey/silver Fungal pycnidia on cane surface Understanding Pathogen Biology & Diversity CANE BLIGHT OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Management • Cultural control recommendations include: • Avoid wounding of primocanes whenever possible • Pinch-off/tip primocanes once at desired height (3-4 ft) • Remove infected canes and old floricanes after harvest • Promote quick drying of the canopy via weed free strip • Avoid nutrition and water stress to plants • Chemical controls recommendations include: • Apply fungicides such as Rally or Pristine after each day of pruning to protect wound site from fungal entry • Whenever possible, avoid pruning prior to rainfall events Understanding Pathogen Biology & Diversity BOTRYTIS FRUIT ROT AND BLOSSOM BLIGHT OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Botrytis Fruit Rot and Blossom Blight • Caused by the fungus Botrytis cinerea • Fungal spores (conidia) readily infect blossoms & ripe fruit • Since conidia are dispersed by wind & rainsplash, persistent rain during bloom can result in significant infections • Can cause devastating preharvest and postharvest fruit rot Oregon St. University NC State University MyIPM App Postharvest fruit rot Botrytis on ripening fruit Conidiophore and conidia Understanding Pathogen Biology & Diversity BOTRYTIS FRUIT ROT AND BLOSSOM BLIGHT OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Management • Cultural controls include: • Practices that create an open canopy to improve air circulation and speed drying of plant surfaces • Chemical controls include: • Fungicide applications at early bloom, full bloom, and pre-harvest to protect flowers and ripening fruit (post bloom and pre-harvest sprays generally not required unless weather is cool and wet). • Fungicides include Rovral, Nevado, Iprodione, Elevate, Switch, Pristine, Luna Tranquility, Ph-D and Captan. • *Fungicide resistance is common with botrytis* Understanding Pathogen Biology & Diversity ROSETTE (DOUBLE BLOSSOM) OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Rosette (Double Blossom) • Caused by the fungus Cercosporella rubi • More colorful, distorted petals produced (double blossoms) • Leafy shoots are produced from infected vegetative buds • Infected flowers on floricanes produce conidia which can infect primocanes in the late spring/summer • Primocanes don’t show symptoms until the next spring. MyIPM App MyIPM App Phil Brannen Distorted petals (Double blossoms) Leafy shoots (witches’-broom) Fungal spores (conidia) Understanding Pathogen Biology & Diversity ROSETTE (DOUBLE BLOSSOM) OUTLINE for Novel Control of Plant Diseases https://berrydealer.com/blackberries/ Management • Cultural controls include: • Removal of infected rosettes before they open to prevent fungal dispersal • Planting disease-free nursery stock away from wild blackberries • Removal of old floricanes immediately after harvest • Chemical controls include: • Applications of fungicides including Switch, Abound, Pristine, and Quilt Xcel from first bloom until harvest. RUST DISEASES ON BLACKBERRY https://berrydealer.com/blackberries/