Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/20/2008
Publication Date: 9/1/2008
Citation: Goenaga, R.J., Mendez, Y. 2008. Is Leaf Blight in Lychee Caused by a Nutritional Deficiency? Proceedings Undergraduate Research Program. Livestock and Environmental Group, Faculty of Agricultural Sciences. University of Puerto Rico, Mayaguez, PR. p. 4-6. Interpretive Summary: Lychee belongs to the Sapindaceae family and is native to Southern China. Little is known about pests and diseases affecting lychee orchards. Leaf spot necrosis has been observed in orchards in Puerto Rico, however no pathogen associated with this condition has been isolated so far. For this reason, nutritional deficiencies have been considered as a potential cause of leaf spot-like symptoms. To determine a cause/effect relationship between lychee nutrition and leaf spot incidence, a greenhouse experiment with nutrient solution omitting either potassium, calcium, magnesium, iron or zinc was carried out. Preliminary results indicate that lychee plants not receiving calcium or magnesium developed symptoms that are similar to those observed in orchards.
Technical Abstract: Lychee belongs to the Sapindaceae family and is native to Southern China. The crop is grown commercially from 17-32° latitude and is usually found at low elevation in the subtropics and from 300-600 m in tropical locations. Foliar necrosis or leaf spot symptoms have been observed in orchards in Puerto Rico; however, efforts to isolate pathogens associated with this disease have been unsuccessful. For this reason, we tested the hypothesis that leaf spot may be caused by nutritional deficiencies. To test this hypothesis, a greenhouse experiment was conducted whereby plants of two lychee clones were grown in sand culture and fertilized with nutrient solutions that omitted either K, Ca, Mg, Fe or Zn. Control plants received all micronutrients. Preliminary results showed no significant differences in plant height, number of leaves or stem diameter between clones. Overall, Ca- and Mg-deficient plants were significantly smaller, had lower number of leaves and smaller stem diameter. Visual observations indicated that Ca- and Mg-deficient plants developed symptoms that are similar to those of leaf spot observed in orchards. Phytopathological analyses are being carried out to discard presence of causal organisms.