33 research outputs found
Wheat: Its water use, production and disease detection and prediction
The author has identified the following significant results. Discussed in this report are: (1) the effects of wheat disease on water use and yield; and (2) the use of ERTS-1 imagery in the evaluation of wheat growth and in the detection of disease severity. Leaf area index was linearly correlated with ratios MSS4:MSS5 and MSS5:MSS6. In an area of severe wheat streak mosaic virus infected fields, correlations of ERTS-1 digital counts with wheat yields and disease severity levels were significant at the 5% level for MSS bands 4 and 5 and band ratios 4/6 and 4/7. Data collection platforms were used to gather meteorological data for the early prediction of rust severity and economic loss
Relationships between temperature and latent periods of rust and leaf-spot diseases of groundnut
The effect of temperature on the latent periods of rust, late leaf spot and early leaf spot diseases of
groundnut caused by Puccinia arachidis, Phaeoisariopsis personata and Cercospora arachidicola.
respectively, was studied. The latent periods (LP) of rust, late leaf spot and early leaf spot ranged from
12-49 days, 13-38 days and 13-39 days, respectively, between 12 C and 33 C An equation relating the
rate of pathogen development (1/LP) to temperature was fitted using daily mean temperatures to provide
three cardinal temperatures: the minimum (7"m,n), optimum (r^pc), and maximum (Tm,,). T^,^ was about
I2°C for rust and about 10°C for the two leaf-spot diseases. Top, for all three diseases was close to 25 C.
7"max was Bl'C for early leaf spot, and extrapolated values for late leaf spot and rust were about 35 and
40°C, respectively
RESUME:Rôle de l'analyse de régression multiple dans le cadre de la protection des plantes moderne
Efeito de alta temperatura no desenvolvimento de Hemileia vastatrix em cafeeiro suscetÃvel Effect of temperature on coffee rust evolution
Foi estudado o efeito de temperaturas elevadas no desenvolvimento da ferrugem do cafeeiro, verificando-se que a exposição de plantas a temperatura próxima de 40ºC por quatro horas durante quatro dias foi suficiente para impedir a evolução da moléstia. PerÃodos menores foram ineficientes para afetar o desenvolvimento do fungo.<br>The development of rust epidemics in tropical conditions of Brazil has been different than previously expected. Despite of high humidity the development is reduced to a minimum during the summer. High temperature was assumed to have a detrimental effect on the rust development. This paper reports the results of a study concerning the effect of high temperature on Hemileia vastatrix development. Temperature treatment of inoculated young plants at 40(0)C for 4 hours in 4 consecutive days was sufficient to prevent rust development. The curative effect was permanent indicating that the fungus was destroyed inside the plant tissue. Practical implications of such results are considered