Which organism is known to infect walnuts and cause blight?

The organism known to infect walnuts and cause blight is Xanthomonas campestris pv. juglandis. This bacterium specifically targets walnut trees, leading to a condition commonly referred to as walnut blight. The symptoms of this disease usually include dark, water-soaked lesions on leaves, fruit, and stems, which can significantly affect the health of the tree and the yield of walnuts.

In contrast, Colletotrichum gloesporioides is associated with anthracnose diseases in various plants but not specifically walnut blight. Oligonychus perseae is a type of mite that primarily affects avocado plants, and Armillaria mellea, commonly known as honey fungus, primarily causes root rot in a variety of trees but is not specifically responsible for blight in walnuts. Understanding the specific pathogens that affect different plants is crucial for effective disease management in agriculture.