4.9.17
CHEMICAL CONTROL OF PAPAYA POWDERY MILDEW

JS TATAGIBA1; JA VENTURA1; JR LIBERATO2; LF MENDONQA1 and H COSTA1

1EMCAPA, Caixa Postal 391, Vitoria-ES, 29010-901, Brazil; 2UENF, CTAA, Laboratorio de Proteao de Plantas, Av. Alberto Lamego, 2000 Campos dos Goytacazes, RJ 28015-620, Brazil

Background and objectives
Papaya (Carica papaya) is one of most important fruit crops in Espirito Santo State, Brazil. Powdery mildew caused by Ovulariopsis sp. is a common disease of papaya first reported in 1994, and may cause severe damage on young plants under field and greenhouse conditions. Premature senescence of infected leaves can result in reduced market quality fruits. Control measures are generally by application of wettable sulfur. However, this may be toxic to plants during hot weather and is not very effective during periods when the disease is severe.

Materials and methods
The fungicides triflumizole 3OPM at 0.015, 0.022 and 0.03% a.i.; methyl thiophanate at 0.07% a.i. and sulfur 52SC at 0.156% a.i. were evaluated under field and greenhouse conditions at Linhares, ES. Water was used as control. Field experiment was arranged in a randomized complete block design with four replicates and six plants/plot of cv. Baixinho de Santa Amalia, spaced 3.2x1.8x1.8 m. A completely random design was arranged in the greenhouse with five replicates and one plant per plot of cv. Sunrise Solo Line 72-12. Disease severity was estimated visually using a scale 0-4 and AUDPC was calculated from July through September 1997.

Results and conclusions
Sulfur and triflumizole gave good powdery mildew control under both conditions with no statistical difference by Duncan's test (P=0.05). Triflumizole is a new fungicide and the tests demonstrated its efficiency at three rates, with no phytotoxicity observed. The results showed the potential benefits of managing powdery mildew by using an IPM approach to timing fungicide applications, induding reduced fungicide inputs, effective disease control and management of fungicide resistance.