5.2.11
KEYPLEX AS A POTENTIAL ELICITOR IN THE CONTROL OF SIGATOKA AND CORDANA LEAF SPOTS OF BANANA

RT MCMILLAN Jr

University of Florida, Tropical Research and Education Center, 18905 SW 280th Street, Homestead, Florida 33031, USA

Background and objectives
Mycosphaerella musicola and Cordana musae, which cause yellow Sigatoka leaf spot and Cordana leaf spot, respectively, are pathogenic to table banana, Musa acuminata in south Florida. Recent research in central Florida documents that KeyPlex reduces greasy spot caused by Mycosphaerella citri of citrus. The objectives of this study were to evaluate the effects of three formulations of KeyPlex 350 on the control of M. musicola and C. musae.

Materials and methods
KeyPlex formulations, KP350 DP#2A, KP350 DP#4, and KP350 DP#5, were evaluated on potted 3-month-old Dwarf Cavendish bananas in the TREC banana collection. Each treatment was combined with the surfactant Kinetic and applied to 10 four-plant replicate plots arranged in a randomized complete block design. All formulations were applied to foliage on July 15 1996 using a 3.8-l sprayer applying approximately 1000 ml per 40 plants in the greenhouse. After 10 days, on July 25 1996, the treated plants were moved to a prepared site in the station banana collection, where the treated plants would be exposed to Sigatoka leaf spot caused by M. musicola (yellow strain) and Cordana leaf spot caused by C. musae.

Results and conclusions
On September 5 1996, four leaves per plant were rated for Sigatoka and Cordana using a scale of 0-5 with 0=no leaf spot, 1=20% area affected, 2=20-40%, 3=40-60%, 4=60-80%, and 5=80-100% area affected. The average severity rating was calculated and statistically analysed. All of the KeyPlex formulations evaluated showed significantly lower Sigatoka and Cordana leaf spot as compared to the untreated control. In all of the treatments the 1.9-l rate was significantly more effective than the 0.9-l rate for Sigatoka and Cordana leaf spot.