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Walnut (Juglans spp.)-Downy Leaf Spot March 2023 Cause The fungus Microstroma juglandis is widespread in western production areas. The disease is more common in wet years and in orchards with poor air circulation. Hyphae of the fungus emerge from stomata, ...
Walnut (Juglans spp.)-Mosses and Lichens See: Hazelnut (Corylus avellana)- Mosses and Lichens ...
Walnut (Juglans spp.)-Nematode, Root-lesion March 2023 Cause Pratylenchus vulnus is a nematode that lives in soil but is rarely found in Oregon. Root-lesion nematodes are migratory endoparasites where part of the population is in soil and part in the root ...
Walnut (Juglans spp.)-Phytophthora Root Rot March 2023 Cause Many Phytophthora species, fungus-like microorganisms, cause a root and root crown rot of walnuts. The more important ones in California are P. cinnamomi and P. citricola. After river flooding, ...
Walnut (Juglans spp.)-Thousand Cankers Disease (Black Walnut Decline) March 2023 Cause A fungal disease (Geosmithia morbida), vectored by the walnut twig beetle (Pityophthorus juglandis), that can cause death of black walnut (Juglans nigra). The disease h ...
Watermelon (Citrullus sp.)-Alternaria Leaf Spot March 2023 Cause Alternaria sp., a fungus. The disease has caused severe losses in Hermiston, OR area fields using overhead irrigation. Symptoms First are irregular brown spots on leaves. Spots may coalesce, ...
Watermelon (Citrullus sp.)-Damping-off March 2023 Cause The fungus-like microorganism, Pythium spp., and the fungus, Rhizoctonia solani, are reported on watermelon. Fusarium spp. also are common damping-off fungal organisms. These pathogens are likely to ...
