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Xanthomonas leaf spot

2008 4-H General Results

 

Figure 1
Figure 1
Figure 2
Figure 2
Figure 3
Figure 3
Figure 4
Figure 4

 

Hedera helix (English Ivy) as well as other plants in the family Araliaceae are susceptible to a bacterial disease called Xanthomonas leaf spot (Xanthomonas campestris pv. Hederae).

 

On English Ivy symptoms begins as circular to irregularly shaped, black, necrotic lesions. (Fig. 1 and 2)

 

As the infection progresses, lesions grow together, or coalesce (Fig 3), giving the plants a blighted appearance (Fig 4). The disease is not considered systemic in English ivy.

To manage the disease:

  • Destroy severely symptomatic plants and debris

  • Increase fertilizer?

    • Nutritional studies of schefflera have indicated that applications of higher than recommended rates of fertilizer produced increased resistance to Xanthomonas leaf spot. As the fertilizer level increased from the recommended level (5 g of Osmocote 19-6-12 per 15 cm pot in 3 months) to five times that rate, the number of lesions per plant decreased linearly. Plant growth was not adversely affected.

  • Apply chemicals, at 14 day intervals , such as

    • Kocide (1.0 lb/100 gal) + Mancozeb ( Manzate 200 at 1.5 lb/gal)

    • Phyton 27

 

Reference:
Chase, A.R., ‘Compendium of Ornamental Foliage Plant Diseases’. APS Press, 1987. pp. 60-61

 


 

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