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Disease Update

By: Bob Kemerait

After the rains at the beginning of this week, I expect farmers will soon be moving quickly to start planting cotton, peanuts and soybeans.  There are two important points that I want to remind you of.

 

  1.  Choose planting date as carefully as you can.  Cool wet soils (or cool wet conditions in the forecast) greatly increase risk of seedling diseases caused by pathogens such as Rhizoctonia solani and Pythium sp.  Planting into hot dry conditions (peanut) greatly increases risk to Aspergilllus crown rot.  I know most of you don’t need to be reminded of this; however choosing planting date based upon CALENDAR DATE can impact risk to tomato spotted wilt; choosing planting date based on SOIL and ENVIRONMENTAL CONDITIONS can have a huge impact on losses to seedling diseases.

 

Best management practices to manage seedling diseases are to establish rapid germination and vigorous growth.  Good seed, good seed treatments, warm soils, good moisture.

 

  1. Corn in my plots is already at the V3-V4 stage and in many commercial fields more advanced than that.  This week I have already had call from a couple of you asking what growers can do AFTER emergence to protect their corn crop from nematodes.  (Read:  “Ouch!  I’ve got a nematode problem and I didn’t put anything out at planting!  What do I do now??”)  The truth is that there is NOTHING that can be done as far as nematicide at this point; all you can do is try to grow the crop.

 

  1. REMINDER:  From number 2 above, growers get only ONE CHANCE to manage important diseases and nematodes affecting corn, cotton, peanuts, soybeans and other crops.  Once the furrow is closed, the variety (resistant or susceptible), planting date, and use of seed treatments, in-furrow products and fumigants are all determined.  There is no going back.