Vol. 11, Issue 9 (2022)

Author(s):
Disha D Desai and PR Patel

Abstract:
Marigold (Tagetes spp.) is one of the most popular traditional flower crops grown commercially in different parts of India. It is also an important commercial crop grown in the South Gujarat. In the present study, field experiment was conducted on epidemiological studies during Kharif 2020 and 2021 at Floriculture Research Farm, Navsari Agricultural University, Navsari, Gujarat, India, on variety Punjab Gainda-1 of marigold under natural conditions. Effect of different weather parameters on percent disease intensity of leaf spot and flower blight incidence of marigold caused due to Alternaria tenuissima were studied using simple correlation technique and regression coefficient to study the development of disease. The maximum percent disease intensity of leaf spot and flower blight incidence were recorded when maximum temperature was in the range of 29.8 °C to 32.3 °C, minimum temperature in the range of 23.2 °C to 24.3 °C, rainfall in the range of 67 mm to 148 mm, evening relative humidity in the range of 81.2% to 85.1% and bright sunshine hours of 2.9 hrs/day to 4.5 hrs/day, as they were most favourable conditions for the rapid development of leaf spot and flower blight of marigold. Correlation matrix revealed that the percent disease intensity and flower blight incidence had highly significant positive correlation with maximum temperature and bright sunshine hours. By working out the stepwise regression it was noticed that at least 90.5 percent variation in percent disease intensity of leaf spot was due to function of weather parameters viz., rainfall and minimum temperature and for flower blight incidence 74.3 percent variation was due to bright sunshine hours. This forecasting models can be used as an aid for farmers by forewarning them prior to disease development and hence managing the disease more efficiently.