Monthly Archives: June 2013
Goss’ Wilt in Corn
Goss’ wilt was found this week in corn damaged from Memorial Day storms in Clay County. I’ve also received pictures that appeared to be Goss’ from crop consultants in other areas of the State. Goss’ wilt lesions have a wavy edge, have a varnished look to them when wet, and have characteristic black “freckles” within and particularly along the lesion edges. We are seeing some plant death due to the systemic version of Goss’ wilt. This can be seen by taking a cross-section of the stem and looking for orange discoloration in the vascular bundles. Because this is a bacterial disease, fungicides are not effective in controlling Goss’ wilt. If you are interested in trying a product that is labeled for treating bacterial diseases in corn, we would recommend you test its effectiveness via on-farm research. Spraying in a paired comparison treatment design will give you a true answer if the product made a difference for you or not.
1-Spray a pass or round with the product (depending on sprayer size) to ensure you can harvest two passes from the center of the treated area.
2-Skip the same amount of distance as you previously sprayed.
Repeat steps 1-2 at least three more times
Mark a few plants in each plot and take photos throughout the growing season to determine if disease progresses or not. You may also wish to keep track of percent of plants affected in each untreated and treated area throughout the season, and check for percent stalk rot and harvest population in each area before harvest as well.
Make sure to harvest two passes from the center of each treated and untreated area. Then compare the weights as shown in the harvest figure. Please let Jenny Rees firstname.lastname@example.org (402) 762-3644 know if you decide to conduct this study and if you have any questions!
Goss’s Wilt from UNL
Sample Submission to UNL Plant and Pest Diagnostic Clinic
Nebraska On-Farm Research Network
Crop Update 6-20-13
The sun has been welcomed and crops are rapidly growing in South Central Nebraska! Corn right now is between V6-V8 (6-8 leaf) for the most part. Quite a few farmers were side-dressing and hilling corn the past two weeks. It never fails that corn looks a little stressed after this as moisture is released from the soil and roots aren’t quite down to deeper moisture.
Installing watermark sensors for irrigation scheduling, we’re finding good moisture to 3 feet in all fields in the area. The driest fields are those which were converted from pasture last year and we want to be watching the third foot especially in those fields. Pivots are running in some fields because corn looks stressed, but there’s plenty of moisture in the soil based on the watermark sensor readings I’m receiving for the entire area. So we would recommend to allow your crops to continue to root down to uptake deeper moisture and nitrogen.
The last few weeks we observed many patterns from fertilizer applications in fields but as corn and root systems are developing, they are growing out of it. We’ve also observed some rapid growth syndrome in plants. This can result from the quick transition we had from cooler temperatures to warmer temperatures, which leads to rapid leaf growth faster than they can emerge from the whorl. Plants may have some twisted whorls and/or lighter discoloration of these leaves, but they will green up upon unfurling and receiving sunlight. This shouldn’t affect yield.
Damping off has been a problem in areas where we had water ponded or saturated conditions for periods of time. We’ve also observed some uneven emergence in various fields from potentially a combination of factors including some cold shock to germinating seedlings.
We began applying sugar to our on-farm research sugar vs. check studies in corn. We will continue to monitor disease and insect pressure in these plots and determine percent stalk rot and yield at the end of the season.
Leaf and stripe rust can be observed in wheat fields in the area and wheat is beginning to turn. We had some problems with wheat streak mosaic virus in the area again affecting producers’ neighboring fields when volunteer wheat wasn’t killed last fall. Alfalfa is beginning to regrow after first cutting and we’re encouraging producers to look for alfalfa weevils. All our crops could really use a nice slow rain right now!
Weed Science Field Day
Hope to see you at this weed science field day at UNL’s South Central Ag Lab near Clay Center on July 2nd! No charge. Please RSVP to (402) 762-4403. More information at: http://scal.unl.edu.