Israeli, Y., Jordan Valley Banana Research Station, Zemach, 15132, Israel
Shabi, E., Department of Plant Pathology, ARO-Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel
Slabaugh, W.R., ISK Biotech Corporation, 11098 W. Highmont Drive, Boise, ID 83709, United States

A possible phytotoxic effect of banana spray oil (BSO) was studied on banana cultivar 'Grand Nain' (Musa spp., AAA subgroup) in Israel where no yellow or black Sigatoka was present. Texaco Spraytex® CT774, at rates of 2.6, 5.2 and 7.8 l ha-1, was applied using simulated aerial application during two consecutive production cycles. Twelve and ten spray cycles were applied during the first and second production cycles, respectively. BSO treatments were compared with the chlorothalonil treatment (BRAVO® 720 2 l ha-1), and an untreated control. No visual phytotoxicity or very subtle symptoms resulted from BSO application even at the highest rate. However, the highest rate of BSO reduced growth rate, delayed flowering by 4 days, and reduced bunch weight by 5.6% (P < 0.05) during the first production cycle when compared with the untreated control. A decrease of 8.4% in bunch weight (P < 0.05) was observed in the second production cycle when the highest BSO rate was compared with the untreated control. Bunch weight losses were directly related to BSO application rates. The number of green leaves at harvest and number of hands per bunch were also significantly reduced during the second production cycle. Chlorothalonil application did not significantly affect any of the parameters measured in this test when compared with the untreated control. This study indicates BSO usage causes a reduction in banana yield. © 1993.