Diseased corn | The CWT Group

Anyone have ideas of what’s going on in this field? The farmer is looking to get an independent agronomist in to evaluate, any recommendations here? Located in southern New England-

thanks!

6 Comments

Rachel Brong on September 3, 2018 at 8:29 am

Pictures to follow-

Larry Jones on September 3, 2018 at 8:42 am

I was able to add Rachel’s pictures to the post? On a post like this, should I open this one up to General and Guests for comments? Please advise.

Jim Zimmerman on September 3, 2018 at 9:03 am

Rachel, Is this a BMR hybrid??? If so, the leaf disease is caused by a fungus. In Pa., we have control by way of helicopter and a fungicide. Also, virtually all tasseled hybrids are threatened by foliar disease. Rain and humidity create the ideal environment for foliar disease and diseases become more severe with continued cloud cover and extended dew cover when you have high dew points in the AM with high humidity. It appears that you may be dealing with a fungal leaf disease such as Gray leaf spot or Northern corn leaf blight. At this point, likely to late for a fungicide fue to crop maturity. Thank you for posting

Jim Zimmerman on September 3, 2018 at 9:09 am

We are seeing this in non BMR as well due to the excess moisture, humidity and high AM dewpoints. Here in Pa., we have had a month of very hi hi h dewpoints near and sometimes above 70. Very high for extended periods of time. Our home on the Northwestern side has had moisture dripping every morning since late June. July and August.

Rachel Brong on September 4, 2018 at 7:40 am

This is not a BMR hybrid, thank you!

Larry Jones on September 4, 2018 at 4:27 pm

I sent the photos to Dean Collamer. The pictures may not be in the same order as the post – sorry.
For full disclosure, FARME Institute as a relationship with GrowmarkFS.

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Larry,

Reviewed the photos. Some observations and comments.

Slide 1. Appears to be corn ear worm damage, a late season pest during larval stage of the insect. Corn ear worm can be effectively controlled with insecticide genetic stack that includes Viptera trait. Just 3 kernels missing/ear translates into 1 bu/A yield loss (shelled corn grain).

Slides 2 & 3. Appears to be gray leaf spot (fungal disease) in #2 and more severe in #3 where spots have coalesced, forming much larger spots. Gray leaf spot can hurt corn yield significantly, or be more cosmetic than yield limiting. Genetic tolerance by the hybrid or foliar fungicide application are the two primary management control measures. Foliar fungicide application results are variable and range from 0-35 bu/A benefit in corn have been measured. For corn silage, improvement in both yield and forage quality have been found following a foliar fungicide application. I’ve seen field results of > 2 T/A silage yield increase.

Slide 4. Appears to be anthracnose (fungal disease) in the corn stalk. Black spots in leopard-like pattern on corn stalks usually follow mechanical damage to the stalk. The usual cause is hail. A black spot forms where there is a stalk wound, allowing a point for fungal infection to penetrate the stalk. No full remedy to this problem, just minimizing the potential for anthracnose infection by application of a fungicide shortly after hail or other mechanical damage has occurred.

Slide 5. Appears to be poor ear tip coverage by the husk. Although I’m not totally sure this is the complete problem shown by this one ear photo. This problem is usually associated with genetic characteristic of a hybrid or genetic characteristic x weather interaction. Hybrid selection (ear tip coverage) is usually the most reliable and effective management method. Genetic variation is wide for ear tip cover by the husk. Many corn hybrid selection guides include this characteristic, but some do not. Ask the supplier if that hybrid characteristic is not included in the hybrid selection guide. Insects, diseases and birds are frequently problematic for hybrids with a lower ear tip coverage rating.

Hope this info is beneficial. Let me know if further follow-up is needed.

Dean

“GROWING YOUR EXPECTATIONS”