Abstract
The purpose of this research was to test effects of bloom-time sprays of MBTA-HCL (MBTA) [Diethyl-2-4-(4-methylbenzyloxy) ethylamine hydrochloride], a new plant growth regulator (PGR), on juice Brix of 'Valencia' sweet orange (Citrus sinensis [L.] Osb.) at harvest. This PGR is being developed by Abbott Laboratories for use on citrus, and will be sold under the product name EcoLyst. In large-plot experiments initiated during flowering in early 1998, mature 'Valencia' trees on either 'Carrizo' citrange or 'Swingle' citrumelo rootstock were sprayed with a 16 ppm solution of MBTA using 100 to 166 gallons of spray per acre. Silwet L-77 adjuvant was added to the spray mixture at 0.05% to increase uptake of the PGR. Eight commercial groves at peak bloom were selected for treatment in the southern flatwoods, Peace River basin, central ridge, and Indian River District. At each location, the PGR treatment was applied by the grower/cooperator using their standard airblast sprayer. Twenty pound fruit samples were harvested three or four times from January to April, 1999. Fruit samples were processed using a commercial extractor before laboratory evaluations of juice Brix, and titratable acid. The PGR treatment increased Brix during the harvest season, without affecting fruit acidity. The maximum increase in Brix exceeded 1.2 degrees; the average increase for all groves and harvests was 0.6 degree Brix. Full United States registration of the commercial product EcoLyst for oranges is pending. Registrations for use on other citrus species are under consideration.
