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News and information from UC Cooperative Extension about alfalfa and forage production.
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Comments:
by joe janak
on June 12, 2013 at 9:26 PM
Good report! I plant dryland alfalfa (retired County Extension Agent in Victoria, Texas) in DaCosta/Contee Complex Clay like a Lake Charles Clay; heavy clay; (that is all the land I own). Been doing it for 20 years. I have to replant every year or two; sometimes three. But no one else grows alfalfa here so it is worth it. 4-6 inch rains are common and usually take out a stand especially in the low spots. Land is virtually flat. I think I do have phytophoria but does it grow/kill in circles? Usually plants die a few days to a week after the heavy rain. I could send you pictures of the plants to help diagnose.  
 
thanks for a response  
 
Joe
by Carol Frate
on June 14, 2013 at 3:18 PM
Joe,  
 
The pattern of Phytophthora in a field is dependent on where the water stands so, if the circles you mention correspond to an area where water puddles or stands - or it is the pattern of a clay soil type, then circles wouldn't be unusual. In our case, where the land is usually leveled with a laser, Phytophthora often appears at the tail end of the irrigation run where water may stand for some time, or where there are unintended low spots, or to parts of the field where there are drainage problems due to soil type or compaction. Circles aren't necessarily the norm but certainly could happen.  
 
The key to further identifying if the problem is Phytophthora is to look at the roots when the plants are wilting and in the process of dying - not after they are dead. Cut the root open and see if there is discoloration internally in the root. I would be happy to look at any photos that you send.  
 
In any case, you should probably try to choose an alfalfa variety with as much resistance to Phytophthora as possible. Rotating out of alfalfa in some of your fields for a year or two might be helpful to the overall health and production of your crop. (Rotation however won't do much to reduce Phytophthora because the fungus survives quite well in soil for a long time).  
 
I am familiar with alfalfa diseases in California but there may be diseases in your part of Texas with which I am not familiar. You might want to check the the Texas A&M website http://plantdiseasehandbook.tamu.edu/industry-specialty/forage-crops/alfalfa-and-sweet-clover/ , which has information on alfalfa and clover diseases in Texas. There is one disease Phymatotricum omnivorum (cotton root rot disease). It is known for appearing in circles and is limited to soils with a pH above 7 and in areas with high soil temperatures. It is most often found in the southwest so I am not sure if this disease is an issue where you are located.
by Bill Wilson
on June 27, 2013 at 4:51 PM
Alfalfa here in Bell County TX just south of Temple. Alfalfa has been grown locally for a long time. When there were a number of small dairies alfalfa was popular. Now only a few farms still have alfalfa.  
With the classic Blackland Clay soil slow water infiltration Phytophthora is a known problem.  
I select varieties that have HR resistance to PRR.  
At an AFGC Conference DR Warren Thompson mentioned that if we really need good resistance for PRR then also select for Aphanomyces resistance. For some reason that helps. In 2007 we had a very wet season and Warren Thompson's comment proved correct.  
Obviously I now select for both PRR & Aphanomyces resistance.  
I have found, for Central Texas, the Alfalfa weevil is less of a problem with FD 4 varieties.
by Bill Wilson alfalfa grower
on June 27, 2013 at 5:01 PM
I would like to contact Joe Janak, now retired Victoria County Agent.
by raselkhan
on January 27, 2016 at 11:50 PM
sete owner write best quality content.I like words that he was thesoil can be saturated due to soil type (heavy clay) or an impediment to drainage such as a hardpan. Because the disease requires saturated soils, Phytophthora-infected plants are often located at the tail end of a field but they can be found anywhere in a field when the right conditions occur.I have a web site and you can see this.
 
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