Effects of Cultivar and Boll Age on Aflatoxin in Cottonseed After Inoculation with Aspergillus flavus at Simulated Exit Holes of the Pink Bollworm

Publisher Website
Google Scholar
Abstract
Seven cultivars of Gossypium hirsutum commonly grown in Arizona, USA, Deltapine (DP) Acala 90 (DP 90), DP 120, DP 77, DP 61, DP 41, DP 20, and McNair 235, became equally contaminated with aflatoxin B1 when 28- to 32-day-old bolls were wounded to simulate exist holes of the pink bollworm and then isolated with conidia of Aspergillus flavus. The cultivar Pima S-6 of G. barbadense, however, became more contaminated than the cultivars of G. hirsutum. In subsequent studies, Pima S-6 became more contaminated than DP 90 when bolls were inoculated at 29-36 days of age and less contaminated when bolls were inoculated at 17-21 days. Aflatoxin was predominantly found in seed from wound-inoculated locks. A. flavus, however, move from inoculated locks to adjacent unwounded locks and contaminate seed produced there with low levels of toxin. Thus, undamaged locks in bolls with exit holes of the pink bollworm may be important sources of contamination in commercial fields. Boll age at inoculation influenced the contamination of both wound-inoculated and adjacent unwounded locks. Wound-inoculated locks of young bolls (13-20 days old at inoculation) became less contaminated than similar locks of bolls 25-32 days old at inoculation. The fungus, however, moved into and contaminated unwounded locks of young bolls more extensively than those of older bolls. Thus, the maturation of the intercarpellary membrane may hinder the interlock spread of A. flavus.