Effect of HLB on Mexican key lime yield in Colima, Mexico

Abstract

Huanglongbing disease (HLB) associated with the bacterium Candidatus Liberibacter asiaticus’ is the most serious threat faced by the Mexican key lime crop [Citrus aurantifolia (Christm) Swingle] in Colima, México. It was detected in April 2010 and soon it spread to all producing areas, causing heavy production losses. In order to characterize yield losses, due to HLB, 700 trees with different percentages of treetop affected were sampled. Using a metal ring of 0.75 m², divided into quadrants, the number of fruits per square meter of treetop (fr m^-2) was quantified. In HLB trees a tend to reduce the fr m^-2 was observed as the percentage of affected treetop increases, both in symptomatic (y= 4.6953x + 53.731; R² 0.8072) and asymptomatic sectors (y= 7.1643x + 67.781; R² 0.9146). Trees without HLB symptoms, averaged 60.3 fr m^-2. In contrast trees with HLB symptoms covering the entire treetop averaged 27.6 fr m^-2, representing a reduction of 45.8%. This paper provides information on how HLB affects yield of Mexican key lime trees from the early stages of infection until when the entire treetop display the symptoms of the disease and helps to explain the yield fall in the production of this citrus in the region.