Texas Upper Gulf Coast
Downy Mildew Fungus & Grain Sorghum
If you farm sorghum between Victoria and Houston, you may be at risk for sorghum downy mildew (SDM), particularly for continuous sorghum. Since about 2000, there have been sporadic outbreaks of SDM, associated with 1) strains of the fungus resistant to metalaxyl, the fungicide commonly used as a seed treatment to control this disease, and 2) planting very susceptible hybrids. Efforts to manage this disease by a monoculture of SDM-resistant hybrids has led to the development of new strains (pathotype) of the fungus that defeat the host resistance. The easiest way to identify an SDM problem in your field is to inspect plants now, while they are still small. The infection occurs while seedlings are emerging from soil. Infected plants are stunted and are difficult to find in a field later in the season because the healthy plants crowd them out. If you think you have SDM, contact your county agent or me (TI), for confirmation and pathotype testing, or to assist with selecting a resistant hybrid for future planting. For more information go to http://sickcrops.tamu.edu to view documents for symptoms and control of SDM.
Submitted by Dr. Tom Isakeit, Extension plant pathologist, College Station, t-isakeit@tamu.edu,
(979) 862-1340.
High Plains
Split Pivot Irrigation Scenarios — Two Crops & Two Planting Dates
With the lack of any deep soil moisture as of mid-April, many irrigated High Plains producers are evaluating strategies to reduce and minimize the risks associated with having one crop under a full pivot. Numerous cropping strategies exist for pairing cotton, corn, and peanut with other crops like grain sorghum, whose planting date, variety/hybrid days to crop maturity, and critical irrigation needs result in primary irrigation requirements at a different time, minimizing if not eliminating overlap of peak timing. Grain sorghum fits favorably in many of these scenarios as a crop with lower production costs and the ability to use limited but timely irrigation. For a PowerPoint discussion of cropping strategies involving grain sorghum, particularly for the Texas South Plains, view the discussion at http://lubbock.tamu.edu/files/2012/04/Texas-High-Plains-Irrigation-Strategies-2012b.pdf.
