Possible Organic Rice Fungicide for Brown Spot and Narrow Brown Leaf Spot

Gowan applies for 24c registration in Texas.

Recently I was contacted by Gowan to provide support as they apply to the Texas Department of Agriculture for a 24c Special Local Need Registration for Badge X2 fungicide.  The product already has a label and OMRI Certification, but it does not have a label use for organic rice in Texas.  If approved this takes care of that issue and we are in hopes that Badge X2 fungicide will get approval for use in this rice season.

According to Gowan, “Badge® X2 is an OMRI listed, patented, dry formulation of copper hydroxide and copper oxychloride.  The copper hydroxide releases copper ions fast for immediate plant protection, while the copper oxychloride slowly releases copper ions for extended residual control PLUS excellent wash-off resistance for the best protection possible during and after rains.”

The 24C Special Local Need registration will for applications of Badge X2 for control of both Brown Spot (Cochliobolus miyabeanus page 79 in the 2023 Rice Handbook) and Narrow Brown Leaf Spot (Cercospora janseana page 78 in the 2023 Rice Handbook)

This link will take you to a proposed 24c label for using Badge X2 in organic rice. Badge X2 Organic Rice Fungicide This label is not approved yet! But it will help you better understand the product and use rates. This is a link to information from a test that Dr. Shane Zhou conducted at the Beaumont Rice Research Center. Click to see study results

Brown spot, caused by Cochliobolus miyabeanus (pictured above), is one of the most common diseases of rice in Texas. The disease is present in seedlings and young and matured plants. The fungal pathogen attacks the coleoptiles, leaves, leaf sheaths, branches of the panicle, glumes, and grain. Although the disease is present at all rice growing stages, it does not necessarily cause significant economic losses. Significant yield losses can occur due to prolonged extremely wet weather, when unfavorable soil conditions such as N deficiency occurs, or when the pathogen attacks panicles. Brown spot can attack seedlings, causing seedling blight. Lesions on leaves can be found throughout the growing season. The pathogen typically produces circular to oval lesions. The lesions vary in size and color. On young leaves, spots are small, dark brown to reddish-brown. On older leaves, spots are relatively large and have a light brown to grey center surrounded by a reddish-brown margin and a gold halo. The lesions may coalesce, killing large areas of infected leaves. Brown spot is usually common in main and ratoon crops and can become severe as plants approach maturity. Symptoms on leaves, leaf sheaths, and hulls are similar. Symptoms also appear on glumes, causing black discoloration. The disease can reduce the number of grain per panicle and the weight of kernels.

Narrow brown leaf spot (also called Cercospora leaf spot) is caused by the fungus Cercospora janseana. The severity of the disease has increased over the years, and it is now considered one of the most important rice diseases in Texas. The disease tends to be more severe at late plantings and in the ratoon crop, causing premature ripening and reducing yield and milling quality.
Generally, the disease is more severe in the ratoon crop than in the main crop.
The fungus attacks the leaves, sheaths, internodes, panicle branches and glumes. On leaf blades, it causes short, linear, narrow, brown lesions that are parallel to the leaf veins. As plants approach maturity, leaf spotting can greatly increase on the more susceptible varieties and result in severe leaf blighting and premature death. Infection of the leaf sheaths results in a large, brown blotch or “net blotch” caused by the browning of the leaf veins. The fungus also can cause a “neck blight,” where the internodal area above and below the node at the base of the panicle becomes light brown to tan. The affected area dies and the kernels in the lower portion of the panicle fail to fill. Low nitrogen levels increase the severity of this disease (a real issue for organic rice producers!).

As more information is made available we will make it available to organic rice producers. As with any OMRI approved organic product you will need to check with your organic certifier before applying to your organic crop.

Author: Bob Whitney, Regents Fellow & Extension Organic Specialist

Agriculturalist, extension educator and researcher, organic agriculture enthusiast and promoter, international program developer, Christian, husband, father and friend.

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