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Bacterial Stripe

Bacterial Stripe

Pseudomonas syringae

bacteria

In a Nutshell

    Lime-green translucent discolorations appear along the leaf veins of lower leavesLesions expand longitudinally and tend to coalesceThe brown necrotic stripes in their centers dry and fall out, giving the leaf a ragged appearanceBacterial ooze is sometimes perceptible in infected tissues

Hosts: %1$s

· Millet · Sorghum · Maize

Symptoms

Lesions appear initially as lime-green to olive-colored translucent discoloration running along the leaf veins of lower leaves. They also gradually start to show in the upper foliage. In optimum weather conditions, these lesions expand longitudinally and tend to coalesce. Bacterial ooze is sometimes perceptible in infected tissues at early stages of the disease. With age, the lesions develop brown necrotic stripes in their centers, that later dry and fall out, giving the leaf a ragged appearance. In some susceptible corn varieties, chlorotic striping of the whorl leaves and distortion of the upper nodes of the plant can be observed.

Trigger

Symptoms depend greatly on the strength of the pathogen, the corn variety and the environmental conditions. The bacteria survives in crops debris in soils, on numerous alternative hosts and weeds (sorghum, rye, clover), and on volunteer crop plants. It is disseminated between plants by irrigation water, wind, or contaminated workers and equipment. The bacteria establishes large populations on leaves before infecting the plant through natural openings or wounds. It can withstand temperatures between 0 and 35 °C, but it thrives in the range 25-30°C. The disease is worst during periods of wet humid weather. When the disease occurs early in the season, some farmers choose to destroy the entire crop by disking.

Biological Control

Alternative options for control of bacterial spot in corn are limited.

Chemical Control

Currently, chemical treatment is limited to copper or copper combined products. Many sprays are only marginally effective, making the disease very difficult to control once an epidemic is underway.

Preventive Measures

    Use seed material from healthy donor plants or from certified sourcesChoose tolerant varieties available in your marketPlant late to avoid wet climatic conditions that spread the diseaseAvoid working in fields when foliage is wetAvoid overhead irrigationClear the field of weeds and alternative hostsDo not compost or leave plant residues near plantationsDisinfect your tools with high-proof alcohol or fire (not both)Remove infected plants immediately and burn their remainsCrop rotation is recommended