Effect of Sowing Date and Bean Cultivars (Ghaffar, Talash, and Sadri) on the Damage by Pod Borer (Helicoverpa armigera) in Agronomic Conditions of Iran

Abstract

Legumes, particularly beans, are a crucial human food source, second only to grains. However, the presence of bean pod borer, Helicoverpa armigera Hubner (Lepidoptera: Noctuidae), poses a significant threat to beans, causing quantitative and qualitative damage each year. To evaluate the effect of sowing date and cultivar on bean pod borer damage in Markazi Province, Iran. A split plot experiment design based on a randomized complete block design (RCBD) with three replications and nine treatments was conducted over two crop years (2020-2021 and 2021-2022). The main plot had three sowing dates: 15 days earlier than the conventional date (early sowing), the conventional date, and 15 days later than the conventional date (late sowing). The subplot focused on three pinto bean cultivars: “Ghaffar,” “Talash,” and, “Sadri.” General, “Sadri” showed the highest mean of the number of larvae in per plant (0.46–0.53) and infection rate, while “Ghaffar” had the lowest mean of number of larvae (0.24–0.30) in both years. The mean of damaged pods was highest (0.42–0.61) in “Sadri” for both years, but lowest in “Ghaffar” (0.27–0.3) for both years. Similarly, the mean of the highest (4.08–4.96) and the lowest (1.54–1.79) damage percentages were observed in “Sadri” and “Ghaffar,” respectively, in both years. “Sadri” had the highest mean number of damaged grains (0.58–0.61) in both years, with “Talash” having the lowest (0.30) in the first year and “Ghaffar” (0.30) in the second year. Moreover, despite the higher pest population and damage, early sowing (May 20) resulted in higher yields in both years. The highest yield was associated to early-sown “Ghaffar” plants whose yield was 3581.00 ± 225.43 kg/ha in the first year and 3571.0 ± 223.40 kg/ha in the second year. Thus, since “Ghaffar” is more pest-tolerant, it can be recommended for cultivation in infested areas.