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United States Department of Agriculture

Agricultural Research Service

Title: Gummy Stem Blight of Melons

Authors
item Miller, M. - TEXAS A&M UNIVERSITY
item Isakeit, T. - TEXAS A&M UNIVERSITY
item Bruton, Benny
item Zhang, Jiuxu

Submitted to: South Texas Melon Committee Annual Research Report
Publication Type: Experiment Station
Publication Acceptance Date: October 12, 1998
Publication Date: N/A

Interpretive Summary: In the Lower Rio Grande Valley of Texas (LRGV), Didymella bryoniae commonly causes lesions in the crown and foliage but rarely on the melon fruit. The spring of 1997 was unusually wet and despite routine benomyl applications, a severe gummy stem blight epidemic occurred resulting in numerous corky-brown lesions (1-3 mm diameter) below the epidermis of cantaloupe fruit. Overall, fruit losses for the spring-1997 season were approximately 68.4% of the cantaloupe crop, amounting to an estimated $15 million loss for south Texas producers. It was determined that greater than 90% of the fungal isolates were benomyl resistant. As a result, several fungicides were evaluated for the control of the gummy stem blight pathogen. The fungicides CGA-245704, Quadris, or Bravo provided significant control of the disease as compared to benomyl and control treatments. In addition, higher marketable yields were obtained in treatments receiving CGA-245704, Quadris, or Bravo. Alternating these fungicide compounds is presently recommended for the control of gummy stem blight of melons in the LRGV. This also reduces the likelihood of developing resistance to these compounds.

Technical Abstract: In the Lower Rio Grande Valley of Texas (LRGV), Didymella bryoniae commonly causes lesions in the crown and foliage but rarely on the melon fruit. The spring of 1997 was unusually wet and despite routine benomyl applications, a severe gummy stem blight epidemic occurred resulting in numerous corky-brown lesions (1-3 mm diameter) below the epidermis of cantaloupe fruit. Overall, fruit losses for the spring-1997 season were approximately 68.4% of the cantaloupe crop, amounting to an estimated $15 million loss for south Texas producers. It was later determined that greater than 90% of the fungal isolates were benomyl resistant. Fungicide evaluations demonstrated that CGA-245704, Quadris, or Bravo provided significantly better control of gummy stem blight as compared to benomyl or control treatments. Significantly higher yields were obtained in treatments receiving CGA-245704, Quadris, or Bravo.

Last Modified: 9/21/2014
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