Abstract

HERNANDEZ G., L et al. Surveillance and forecast preliminary study for black sigatoka (Mycosphaerella fijiensis Morelet) disease in Musa AAB cv Hartón plantain crop in "Macagua-Jurimiquire", Yaracuy state. Rev. Fac. Agron. [online]. 2005, vol.22, n.4, pp.325-339. ISSN 0378-7818.

To establish a survey and forecast program for black sigatoka disease in Musa AAB cv Harton plantain stablished on growing in small production system. The severity average index (SAI), youngest spotted leaf position (YSLP), foliar emission (FE), daily precipitation (PP), relative humidity (RH), evaporation (EVA), maximun and minimun temperature (Tmax and Tmin), cloudiness (CL), insolation and radiation were determined every 2 weeks. The averages per month for some of these climatic variables were: PP 143.5 mm; Tmax 29°C; Tmin 21°C and RH 78.5%. The SAI was correlated to the climatic variables during 8-consecutive weeks, previous to evaluate the disease severity. The variable with the best correlated coeficients were analized by using multiple regression method. The higher values of SAI were observed in January 1.31; May 1.14; September 1.32; October 1.20 and December 1.21 during this study. The YSLP average was 5.38 with a maximun of 6.88 and minimum of 4.40; while the SAI average was 1.13 with a minimum of 0.64 and a maximum of 1.32. A negative correlation were observed between SAI and YSLP (r = - 0.7132), and between SAI and FE (r = - 0.2556). The disease behavior is 33,32% explained by the following equation: SAI = 3.7241** - 0.0047**CL 0.0015**Tmin + 2.019**RH 0.0051**EVA, according to acumulated values during 6-consecutive weeks previous to the last week of SAI observation.

Keywords : epidemiology; disease incidence; pest integrate management; climate; black sigatoka disease; Musa AAB; Venezuela.