Rice disease research in organic production systems

Authors: ZHOU, XIN - Texas A&M Agrilife; McClung, Anna

Submitted to: Texas Experiment Station Field Day Handout
Publication Type: Experiment Station
Publication Acceptance Date: 5/30/2010
Publication Date: 5/31/2010
Citation: Zhou, X.G., Mcclung, A.M. 2010. Rice disease research in organic production systems. Texas Experiment Station Field Day Handout. X (4): 21-22.

Interpretive Summary:

Technical Abstract: Organic rice production has increased significantly in the U. S. with 35,000 acres currently under production. Texas organic rice acreage has been increasing steadily over the last 10 years with acreage in 2009 reaching 16,000, accounting for approximately 10% of the total Texas rice acreage. Control of pests including weeds and diseases in organic rice is a particular challenge due to the lack of effective organic pesticides. The objectives of this research were to evaluate the effects of organic versus conventional management on common foliar diseases and to examine the impact of organic fertilizers on narrow brown leaf spot in organic rice. Twenty-four rice cultivars and lines were grown under recommended organic or conventional management systems at Beaumont, TX in 2009. These cultivars and lines differentiated their responses to narrow brown leaf spot and brown leaf spot under organic and conventional production conditions. However, both foliar diseases tended to be more severe on most of the cultivars and lines in organic rice than in conventional rice. For example, Cocodrie and Presidio were rated susceptible to both diseases under organic conditions while they were rated moderately susceptible to brown leaf spot and moderately resistant to narrow brown leaf spot under conventional conditions. An organic trial comparing the fertilizers AgriCycle (4-2-7, N-P-K), Nature Safe (13-0-0) and Rhizogen (7-2-1) at 0, 500, 1000 and 1500 lb/A was conducted on the rice cultivar Presidio in Beaumont, TX in 2009. Applications of AgriCycle at 1,000 lb/A and Rhizogen and NatureSafe at 500 lb/A or above significantly reduced narrow brown leaf spot in organic rice (Fig. 1). The disease quantitatively decreased with the increase of total net nitrogen applied. This study indicates that organically produced rice is more vulnerable to infection by foliar diseases than conventionally produced rice. This may be partially due to nitrogen deficiency as a result of using slow release organic fertilizers. Developing organic cropping systems which enhance soil nutrient quality may be a means for improving yield under organic management as well as improving foliar disease control. Research conducted by Drs. Xin-Gen Zhou, and Anna McClung. For more information, please contact Xin-Gen (Shane) Zhou at [phone] ext. 2210 or [e-mail].