Mailhot D J, Marois J J, Wright D L
North Florida Research and Education Center, University of Florida, IFAS, Quincy 32351.
Plant Pathology Department, North Florida Research and Education Center, University of Florida, IFAS, Quincy 32351.
Plant Dis. 2007 Nov;91(11):1423-1429. doi: 10.1094/PDIS-91-11-1423.
Cotton (Gossypium hirsutum) fiber is sometimes affected by hardlock, which is characterized by a failure of the fiber to expand outward from the boll at maturity. Because affected fiber is inaccessible to mechanical harvesters, yield loss can be considerable. Hardlock has been linked to infection by Fusarium verticillioides. The involvement of flower thrips (Frankliniella spp.), which are commonly found in cotton flowers, was explored. At 1100 h, approximately 10% of cotton flowers contained thrips that were carrying F. verticillioides. The effect of thrips and/or Fusarium in flowers and bolls was explored under greenhouse conditions. Exposing flowers to Fusarium and thrips resulted in bolls with the most severe symptoms. Exposure to either Fusarium or thrips alone resulted in more hardlock than was noted in the control group. The impact of thrips was also evaluated under field conditions. Field plots were treated with insecticides, a fungicide, both, or left untreated. Insecticides reduced thrips numbers and reduced hardlock severity. The fungicide had no impact on thrips numbers and was less effective at reducing hardlock. Combining insecticide and fungicide applications was no more effective than using insecticides alone, although it more frequently increased yield. The untreated control plots generally had the most severe hardlock and lowest yields. Reducing hardlock severity resulted in higher yields, although not consistently. These studies suggest that thrips increase the severity of hardlock, and reducing their numbers may diminish hardlock severity.
棉花（陆地棉）纤维有时会受到硬锁病的影响，其特征是纤维在成熟时无法从棉铃中向外伸展。由于受影响的纤维无法被机械收割机采收，产量损失可能相当大。硬锁病与轮枝镰孢菌感染有关。人们对常见于棉花花朵中的花蓟马（西花蓟马属）的作用进行了探究。在上午11点时，约10%的棉花花朵中有携带轮枝镰孢菌的蓟马。在温室条件下研究了蓟马和/或镰孢菌对花朵和棉铃的影响。让花朵接触镰孢菌和蓟马会导致棉铃出现最严重的症状。单独接触镰孢菌或蓟马导致的硬锁病都比对照组更严重。还在田间条件下评估了蓟马的影响。田间地块分别用杀虫剂、杀菌剂、两者都用或不处理。杀虫剂减少了蓟马数量并降低了硬锁病的严重程度。杀菌剂对蓟马数量没有影响，在减轻硬锁病方面效果较差。虽然联合使用杀虫剂和杀菌剂更常提高产量，但并不比单独使用杀虫剂更有效。未处理的对照地块通常硬锁病最严重且产量最低。降低硬锁病的严重程度会提高产量，不过并非始终如此。这些研究表明，蓟马会加重硬锁病的严重程度，减少其数量可能会减轻硬锁病的严重程度。
