Plant Disease Management Handbook

By O. Neher and C. M. Ocamb

Cause The fungus, Erysiphe betae (syn = E. polygoni, Microsphaera betae), affects plants in the Polygonaceae. The disease has been widespread in several Western States since 1974. Fungal spores may blow in from overwintering sources. Overwintered infected seed beets may also be sources of infections. The fungus tolerates a wide range of environmental conditions.

By O. Neher and C. M. Ocamb

Cause The fungus-like soilborne organisms, Phytophthora drechsleri and Pythium aphanidermatum, cause root rot primarily in waterlogged soils at high temperatures. Low areas of the field are where these two diseases are most often found.

By O. Neher and C. M. Ocamb

Cause Meloidogyne hapla is a sedentary endoparasite; only second-stage juveniles (the infective stage) and adult males (which may be rare) are in soil.

By O. Neher and C. M. Ocamb

Cause Heterodera schachtii is a sedentary endoparasite with a relatively small host range. Other crop hosts are mangel-wurzel, table beet, cabbage, cauliflower, Brussels sprouts, broccoli, rape, turnip, rutabaga, and radish. Weed hosts are dock, knotweed, lambsquarters, mustard, nightshade, purslane, saltbush, and red root. Any of these that overwinter may be reservoirs for the pests and may counteract much of the value of crop rotation.

Cause A deficiency in the minor, nonmobile element boron.

Symptoms A necrotic cross-hatching inside the leaf petiole. Young leaves turn brown and die, resulting in a rosette of small dead leaves at the top of the beet. In the fleshy root, internal and external black spots of necrotic tissue develop.

Cultural control

Cause The soilborne fungus, Fusarium oxysporum f. sp. betae. This pathogen can survive many years as hardy spores (chlamydospores) in soil or can persist as colonized plant debris. It also can survive on many weedy hosts. Periodically, the disease can be severe.

By O. Neher and C. M. Ocamb (Group M1)

By O. Neher and C. M. Ocamb

By O. Neher and C. M. Ocamb