2018 ASHS Annual Conference

Pecan growers experience profitability loses due to nut vivipary when orchards are growing under warm and dry conditions. The goal of this study was to evaluate the effect of three plant growth regulators on pecan nut yield and vivipary. Treatments evaluated were: 1) Azoxystrobin (AZ, 150 g per ha), 2) Trinexapac ethyl (TE, 500 g per ha), 3) Paclobutrazol (PB, 125 g per ha), 4) the mixture of treatments 1 and 2, AZ+TE, and 5) the Control, without application. Treatments were sprayed to drip irrigated adult ‘Wichita’ pecan trees (~40 years old) using 1800 L per ha of water and an adjuvant was added at a rate of 0.5 ml per liter. Treatments were applied three times, and application dates were August 31, September 13 and September 20 of 2011. Pecan nut yield per hectare and nut vivipary was evaluated in 2011 and the effect of treatments on pecan nut yield in 2012 and the cumulative yield was also measured. Nut vivipary percent was 49.3±4.5% in the control treatment. Treatments TE and AZ+TE have 49.3±5.0% and 45.1±5.6% percent of nut vivipary, respectively. Treatments AZ and PB have the lower pecan nut vivipary with 34.5±3.1 and 31.0±1.5%, respectively; about 30% lower than the Control treatment. Pecan nut yield (non viviparous nuts), ranged from 1878 Kg per ha in the Control treatment Kg per ha to 2201 Kg per ha in the AZ+TE treatment, but differences were not significant. Nevertheless yield in 2012 ranged from 725 Kg per ha to 1888 Kg per ha differences were not significant, and the same occurred with the cumulative nut yield. According to results, nut vivipary levels can reach up to 49.3% in this hot and dry region located in the northwest of Mexico; and that some plant growth regulator evaluated could decrease nut vivipary of pecan trees cultivated in these conditions, hot and dry.