Diseases

Enterobacter bulb decay forms after onions have been stored. The symptoms can appear as water-soaked scales (initial photo). Symptoms also present as light brown to dark brown scales. Enterobacter spp. can also cause scales to shrink or collapse (bottom photo).

Enterobacter spp. can infect onion leaves as well. This presents as light brown to dark brown discoloration and soft rot, eventually leading to collapsed, necrotic leaves.

IYSV is spread by thrips. Lesions start out at thrip feeding points. These start as light and dark rings or diamond shaped lesions. These infected areas can grow into each other and girdle the leaves. This ultimately causes the leaves to collapse, brown and die.

Pantoea agglomerans is a bacterial pathogen that causes bulb rot and leaf blight in onions. When present in the bulb, this bacteria typically causes the inner scales to turn a watery yellow to brown color.

Pantoea agglomerans is a bacterial pathogen that causes bulb rot and leaf blight in onions. When present in the bulb, this bacteria typically causes the inner scales to turn a watery yellow to brown color. Another symptom of this pathogen are water-soaked lesions.

Pantoea agglomerans is a bacterial pathogen that causes bulb rot and leaf blight in onions. Bacterial leaf blight can present very similarly to leaf blight caused by IYSV.

Pseudomonas spp. presents in the neck or outside scales initially and spreads to the inner scales. The pathogen presents as water-soaked lesions, usually with a yellowish-brown color. In some onions the lesions appear grey. Onions fertilized too much and onions with higher nitrogen content are more susceptible to Pseudomonas spp.

Pseudomonas spp. causes bacterial leaf blight and leaf spot on onion leaves. These leaf spots start white and transition to a brown color.

Pythium intermedium causes damping off and root rots in onions. Symptoms are water-soaked lesions on the roots and lower scales. Roots and older scales on seedlings may turn black. Older plants can exhibit stunting, yellowing and wilting of leaves.

Pythium intermedium causes damping off and root rots in onions. Symptoms are water-soaked lesions on the roots and lower scales. Roots and older scales on seedlings may turn black. Older plants can exhibit stunting, yellowing and wilting of leaves.

Rahnella sp. is an onion associated bacteria. It can cause soft rot in bulbs. Scales of infected bulbs begin showing symptoms of watery and/or yellow discoloration. This progresses into brown to dark brown discoloration and collapsed or shrunken scales. The very rotten bulb may be affected by multiple pathogens, not only Rahnella spp.

Rahnella sp. is an onion associated bacteria. It can cause soft rot in bulbs. Scales of infected bulbs begin showing symptoms of watery and/or yellow discoloration. This progresses into brown to dark brown discoloration and collapsed or shrunken scales.

Stemphylium vesicarium causes two types of onion leaf blight, brown oval lesions and yellow mottle lesions. These brown lesions can lead to the development of the yellow lesions.

Stemphylium vesicarium causes two types of onion leaf blight, brown oval lesions and yellow mottle lesions. These brown lesions can lead to the development of the yellow lesions.

Stemphylium vesicarium causes two types of onion leaf blight, brown oval lesions and yellow mottle lesions. These brown lesions can lead to the development of the yellow lesions.

Stemphylium vesicarium causes two types of onion leaf blight, brown oval lesions and yellow mottle lesions. These brown lesions can lead to the development of the yellow lesions.

Stemphylium vesicarium causes two types of onion leaf blight, brown oval lesions and yellow mottle lesions. These brown lesions can lead to the development of the yellow lesions.

Stemphylium vesicarium causes two types of onion leaf blight, brown oval lesions and yellow mottle lesions. These brown lesions can lead to the development of the yellow lesions.