Young summer leaves of uniform size on a single tree were tagged and then picked at intervals as they matured. Prior to the time of maximum leaf expansion, the relation between Fe and chlorophyll concentrations changed rapidly in the direction of increased chlorophyll per unit of Fe. Samples from three orchards taken in September revealed a correlation coefficient of .70 between Fe and chloroph...

Fruit-set on trees of the Fuerte avocado in relation to distance from trees of the Hass and Topa Topa varieties in a Southern California grove was analyzed. The presence of adjacent trees of a second variety was associated with an average Fuerte yield increase of about 40%. In certain years there were statistically significant yield decreases on the Fuerte trees adjacent to other varieties. No ...

Resequencing studies provide the ultimate resolution of genetic diversity because they identify all mutations in a gene that are present within the sampled individuals. We report a resequencing study of Persea americana, a subtropical tree species native to Meso- and Central America and the progenitor of cultivated avocado. The sample includes 21 wild accessions from Mexico, Costa Rica, Ecuador...

Avocado (Persea americana Mill. cv Lula) is a climacteric fruit that exhibits a rise in ethylene as the fruit ripens. This rise in ethylene is followed by an increase in abscisic acid (ABA), with the highest level occurring just after the peak in ethylene production. ABA is synthesized from the cleavage of carotenoid precursors. The cleavage of carotenoid precursors produces xanthoxin, which ca...

Laurel wilt kills members of the Lauraceae plant family in the southeastern United States. It is caused by Raffaelea lauricola T.C. Harr., Fraedrich and Aghayeva, a nutritional fungal symbiont of an invasive Asian ambrosia beetle, Xyleborus glabratus Eichhoff, which was detected in Port Wentworth, Georgia, in 2002. The beetle is the primary vector of R. lauricola in forests along the southeaste...

Upon initiation of ripening in avocado fruit (Persea americana Mill. cv Hass) with 10 microliters/liter ethylene, polysome prevalence and associated poly(A)(+) mRNA increase approximately 3-fold early in the respiratory climacteric and drop off to preclimacteric levels at the peak of the respiratory climacteric. The increase in poly(A)(+) mRNA on polysomes early in the respiratory climacteric c...

Two PCR primer pairs were designed to amplify rRNA genes (rDNA) from all four major phyla of fungi: Ascomycota, Basidiomycota, Chytridomycota, and Zygomycota. PCRs performed with these primers showed that both pairs amplify DNA from organisms representing the major taxonomic groups of fungi but not from nonfungal sources. To test the ability of the primers to amplify fungal rDNA from environmen...

Lime-induced iron chlorosis in citrus and avocado trees may be controlled by chelating agents, such as EDTA-ethylene-diaminetetraacetic acid. Chelating agents have the ability to form complex compounds with metal ions-iron, zinc, manganese, and magnesium-holding the metals in a soluble form in various degrees of tenacity. Iron is held most firmly and, for this reason, the prospects may be best ...

Chilling injury (CI) symptoms in avocado (Persea americana Mill.) fruit, expressed as mesocarp discoloration, were found to be associated with embryo growth and ethylene production during cold storage. In cvs Ettinger and Arad most mesocarp discoloration was located close to the base of the seed and was induced by ethylene treatment in seeded avocado fruit. However, ethylene did not increase me...