Due to bacterial reproduction, they are everywhere, including all over asymptomatic plants. Bacterial diseases of the foliage are favored by prolonged periods of leaf wetness, and high relative humidity. Regardless of which bacteria you are battling, there are certain key management strategies that reduce bacterial growth and spread. A laboratory diagnosis is needed to confirm which type of bacterial problem your plants have. In fact, host specificity is not known to exist. Neither is the soft rot pathogen of bulbs and many bedding plants, Pectobacterium carotovorum. Unlike the host specific Xanthomonas species, P. Unfortunately, this pathogen produces symptoms that look a lot like Pseudomonas cichorii, a major pathogen on chrysanthemum, ivy, basil, and other plants. So, if you have infected zinnias, this pathogen will not spread to your tomatoes or peppers. zinniae infects zinna, whereas Xanthomonas vesicatoria infects tomatoes and peppers. A key point to remember is that different species of Xanthomonas or Pseudomonas infect different species plants, which is indicated by the term ‘pathovar’, meaning variety of bacteria pathogenic to one host. Plant HostĮven with a microscope, most plant infecting bacteria look surprisingly boring, like a pill–A very, very small pill. Plant hosts and the causal bacterium that cause disease commonly observed in Indiana. In nursery crops, the fire blight pathogen, Erwinia amylovora, is a common and devastating problem (Table 1). In the last year, we’ve been seeing a lot of Xanthomonas leaf spot and Pseudomonas leaf spot on bedding plants, particularly begonia, in addition to vegetable and herb starts. As lesions coalesce, the damage may appear more like blight, as opposed to a discrete spot (Fig. Yellow or red halos often develop around the lesion. These symptoms usually appear between the leaf veins resulting in discrete, angular spots. Crown gall.Īfter the bacteria get into the leaves and begin to reproduce, symptoms develop. Bacterial leaf spot of peach also infects and defoliates ornamental plums and cherries d. angular leaf spot on hydrangea caused by Xanthomonas c. Fire blight on cotoneaster causes blackened foliage b.

Bacterial blight of gernaium