Evaluation and Validation of Teb-Cast Forecast System to Manage Tomato Early Blight in Egypt

Abstract

Tomato (Lycopersicon esculentum Mill.) is considered one of the main vegetable cash crop for both local consumption and exportation in Egypt. The most important disease infect tomato plants is early blight caused by Alternaria solani which also attacks several nightshade crops including potato and eggplant. Under favourable weather conditions the disease cycle takes about one week.This rapid reproduction cycle can expand the disease so rapidly and completely defoliate tomato plants causing a severe losses in yield. Therefore, a 7-10 day spray schedule with protecting fungicides is a traditional and effective system to control tomato early blight. Consumer concern about agro-chemical residues is strong in Egypt, and particularly relevant for fresh consumed products, including tomato. This consumer concern for food safety and the environment has lead to certified schemes for good agricultural practices such as disease forecast. A computerized forecast model named by the authors (TEB-Cast) is an integral linking based on short term observations over several tomato growing seasons , analyzing the correlation between 24 hour microclimate data collected throughout real time automatic Agroweather station (Adcon Telemetry A733 AddWave) , was evaluated and validated under both computer lab. (workstation) and open field in 2005 and 2006 growing seasons .The results indicated that TEB-Cast forecast model correctly timed the first spray and the disease daily infection potential and significantly reduced the number of sprays compared with the routine schedule fungicide applications in both 2005 and 2006 growing seasons respectively. The basic roles of system analysis for model evaluation and validation are discussed in details.