Cotton (&amp;lt;i&amp;gt;Gossypium hirsutum&amp;lt;/i&amp;gt; L.) Boll Rot and Associated Microorganisms in South Texas Fields

Greta Schuster,Kendal Field-Huey,Enrique G Medrano

doi:10.4236/as.2016.710068

Abstract

A rise in cotton boll rot in south Texas has been generally associated with increased yield losses. Here, we measured boll rot incidence during two growing seasons (2011 and 2012) at a south Texas (Kleberg County) research farm Variety Trial and in producer fields. The Variety Trial was conducted to compare boll rot susceptibility between five current cultivars. The commercial fields surveyed were located along the Coastal Bend (Wharton County) and Rio Grande Valley regions (Cameron and Willacy Counties). Bolls with evidence of external damage potentially inflicted by piercing-sucking insect vectors were dissected for disease detection and plated for microorganism isolation and characterization. Microbial isolates were putatively identified based on standard fatty acid methyl ester profile analysis. In the Variety Trial, the highest incidence of disease occurred in July for both growing seasons, and significant differences in susceptibility to boll rot between cultivars were determined (P < 0.05). The highest boll disease incidence was 28% in August 2012 for the Coastal Bend region and also 28% but in June 2011 in the Rio Grande Valley. Bacillus species were predominately isolated and associated with boll rot for all the fields studied over the 2 year period. This is the first report to directly study the occurrence of boll rot in south Texas and associate Bacillus spp. as a potential and prevalent causative agent(s).

Highlights

IntroductionIn 2010, the United States harvested 10.7 million cotton acres with Texas producing over half of that total acreage [2]
In the Variety Trial, the highest incidence of disease occurred in July for both growing seasons, and significant differences in susceptibility to boll rot between cultivars were determined (P < 0.05)
In August 2012, bolls from the Coastal Bend counties had the highest level of punctures per locule with a mean of 3.6 (Figure 8) and disease severity mean value of 0.45 (Figure 9)

Summary

Introduction

In 2010, the United States harvested 10.7 million cotton acres with Texas producing over half of that total acreage [2]. In Texas, cotton is the leading cash crop grown on over 5 million acres [3]. The south Texas Coastal Bend and Rio Grande Valley regions produce approximately 11% of the state’s total cotton crop [3]. Between 2010 and 2011 there was an estimated yield loss of 100,153 to 182,708 bales of US cotton due to boll rot [9] [10] and the trend has since continued. Boll rot is a term used to describe various symptoms or reactions to infections by various plant pathogenic microorganisms affecting developing cotton bolls [11]. The inner boll infection was reportedly associated with opportunistic bacteria with Pantoea agglomerans as the main agent in certain regions [14] [15] [16]

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Conclusion