Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 1, 2002
Publication Date: January 31, 2002
Citation: Smith, B.J. 2002. Susceptibility of vegetative tissues of fruit and vegetable hosts to infection by various Colletotrichum species. Acta Horticulturae. 567:631-634. Interpretive Summary: Strawberry anthracnose disease (incited by Colletotrichum spp.) cause severe economic losses for strawberry growers in the southeastern United States. Despite efforts to avoid these disease by obtaining anthracnose-free transplants from northern nurseries, anthracnose continues to be a major problem. Since Colletotrichum spp. cause diseases of many other fruit and vegetable crops (peaches, apples, blueberry, tomato, pepper, cucumber), the possibility exits that Colletotrichum infection in strawberry fields may be coming from adjacent crops. In this study 37 Colletotrichum isolates representing nine species from 12 hosts were wound inoculated onto the stems and leaves of strawberry, blueberry, blackberry, muscadine grape, tomato, and pepper. Although many of the isolates caused some lesion development on all the hosts except pepper, the lesions were usually small. These results indicate there is a slight possibility that the initial Colletotrichum inoculum in strawberry fields can come from other crops. However, the small size of lesions incited by most of the isolates suggest that this is not the usual source of primary inoculum. The primary source of inoculum appears to be on transplants from the nurseries.
Technical Abstract: Colletotrichum species cause many serious diseases of fruits and vegetables worldwide. Three species, C. acutatum, C. fragariae, and C. gloeosporioides, are major pathogens of strawberry causing anthracnose fruit and crown rots. One disease control strategy is to establish new strawberry fields with "clean" anthracnose- free plants. To test the hypothesis that Colletotrichum species may move from host to host, 37 Colletotrichum isolates representing nine species collected from 12 hosts were wound inoculated onto strawberry, blueberry, blackberry, muscadine grape, tomato and pepper. Inoculated plants were incubated at 100% RH and 25C for 48 hr. Symptoms were rated after 30 days. The four C. fragariae isolates were most aggressive causing lesion development at an average of 38% of inoculation sites on all hosts except pepper. The percentage infection for the other species was C. capsici 25%, C. gloeosporioides 18%, C. acutatum 15%, C. destructivum 11%, C. truncatum 9%, C. coccodes 8%, C. higginsianun 6%, and C. orbiculare 5%. More lesions developed on stems than on leaves. Strawberry was the most susceptible host with 58% of petiole and 14% of leaf inoculations resulting in lesion development. Pepper was the most resistant host with no symptom development on leaves or stems following inoculation with any isolate. Lesion development with all 37 isolates on stem tissues for the other hosts was blueberry 34%, muscadine grape 26%, blackberry 19% and tomato 13%. The most aggressive of the 16 C. acutatum isolates originated from tomato and pepper.