Osekre Enoch A, Wright David L, Marois James J, Funderburk Joe
University of Florida, 155 Research Road, Quincy, FL 32351, USA.
J Econ Entomol. 2009 Jun;102(3):887-96. doi: 10.1603/029.102.0305.
Cotton hardlock caused by Fusarium verticillioides (Sacc. Nirenberg) can reduce cotton, Gossypium hirsutum L., yields > 70% in the southeastern United States. The spores infect flowers on the day of pollination, resulting in hardlock, which is the failure of the fiber to fluff as the boll opens at maturity. Frankliniella spp. Thrips (Thysanoptera: Thripidae) inhabiting the flowers are hypothesized to increase hardlock by spreading the conidia or by creating entranceways for the germinating Fusarium conidia. Experiments were conducted at Marianna and Quincy in Florida in 2006 and 2007 to determine whether there was a relationship between the number of adult and larval thrips inhabiting the flowers of cotton and the incidence of cotton hardlock. Frankliniella tritici (Fitch) was > 98% of the adult thrips in the samples at both locations each year. The adults of Frankliniella bispinosa (Morgan) and Frankliniella occidentalis (Pergande) also were collected. There were no significant regression relationships between weekly mean densities of thrips in the flowers and the incidence of cotton hardlock at harvest in any of the experiments. Additional experiments were conducted at each location in 2006 and 2007 to determine whether weekly applications during flowering of the insecticide lambda-cyhalothrin, the fungicide thiophanate methyl, and the combination of the two reduced the incidence of cotton hardlock at harvest. Applications of the insecticide significantly reduced the numbers of adult F. tritici, the number of thrips larvae, and the incidence of hardlock at harvest. Applications of the insecticide were as affective as applications of the insecticide plus fungicide. In one experiment, applications of the fungicide reduced the incidence of hardlock at harvest. Applications of the insecticide usually significantly increased the number of adult F. occidentalis. None of the pesticide treatments significantly affected the numbers of the key thrips predator Orius insidiosus (Say). We conclude that insecticidal control of the adults and larvae of F. tritici during flowering reduced the incidence of cotton hardlock. However, there were no significant regression relationships between the incidence of cotton hardlock at harvest and the number of thrips in the flowers.
由轮枝镰孢菌（Sacc. Nirenberg）引起的棉花硬籽病可使美国东南部的陆地棉（Gossypium hirsutum L.）产量降低70%以上。孢子在授粉当天感染花朵，导致硬籽病，即棉铃成熟开裂时纤维无法蓬松。据推测，栖息在花朵上的花蓟马属（Frankliniella spp.）蓟马（缨翅目：蓟马科）通过传播分生孢子或为萌发的镰孢菌分生孢子创造入口来增加硬籽病的发生率。2006年和2007年在佛罗里达州的玛丽安娜和昆西进行了试验，以确定栖息在棉花花朵上的成虫和幼虫蓟马数量与棉花硬籽病发生率之间是否存在关联。每年在这两个地点的样本中，小麦花蓟马（Frankliniella tritici (Fitch)）占成虫蓟马的比例均超过98%。同时还采集到了双棘花蓟马（Frankliniella bispinosa (Morgan)）和西花蓟马（Frankliniella occidentalis (Pergande)）的成虫。在任何试验中，花朵中蓟马的周平均密度与收获时棉花硬籽病的发生率之间均无显著的回归关系。2006年和2007年在每个地点还进行了额外试验，以确定在花期每周施用氯氟氰菊酯杀虫剂、甲基托布津杀菌剂以及二者的组合是否能降低收获时棉花硬籽病发生率。施用杀虫剂显著减少了小麦花蓟马成虫数量、蓟马幼虫数量以及收获时硬籽病的发生率。施用杀虫剂与施用杀虫剂加杀菌剂的效果相同。在一项试验中，施用杀菌剂降低了收获时硬籽病的发生率。施用杀虫剂通常会显著增加西花蓟马成虫数量。没有一种农药处理对关键蓟马捕食者暗黑赤眼蜂（Orius insidiosus (Say)）的数量有显著影响。我们得出结论，花期对小麦花蓟马成虫和幼虫进行杀虫控制可降低棉花硬籽病的发生率。然而，收获时棉花硬籽病的发生率与花朵中蓟马数量之间并无显著的回归关系。
