Category Archives: Corn
A few things to think about with regards to disease and nematode management in preparation for the 2017 field season.
La Nina: Our UGA Extension climatologist Pam Knox has good information available on our current conditions, but here are my thoughts:
We are currently in a “weak” La Nina situation, “weak” because the equatorial waters of the cost of Ecuador are more than a half degree COOLER than normal. As best I can tell, the waters have been about 7/10 of a degree cooler which barely qualifies as a La Nina (as opposed to last year where we had a robust and sure-enough El Nino). So what does this mean? During La Nina years, the Southeast tends to (“tends to” means more often than not, but not always..) experience warmer and drier winters. Because we have a weak La Nina, this forecast could change.
How does our current “La Nina” impact our recommendations?
- Drier is not a good thing as it may mean we don’t fill up irrigation ponds for next year. It my mean we have a lot of trouble establishing cover crops this fall.
- Warmer temperatures may mean that kudzu, volunteer peanuts, corn, cotton-regrowth, etc. pathogens (like those that cause soybean rust and southern corn rust) may survive and increase longer than they would with an earlier “killing” frost. Also, as long as the crops and volunteers are active in the field, nematode populations can continue to increase and build. This will lead to larger populations for next season. Once the plants are killed, the nematodes can no longer feed. Once soil temps drop below 65F, the activity of the todes drops off as well.
- We may get some very cold weather soon, so we may not need to worry that much; however the general prediction is that we will have a warmer winter.
- The weather this winter will have some effect on TSWV and insects for next year. It remains to be seen what and how… but it will impact them.
UGA Entomologist Dr. Mike Toews is getting questions about treating shelled corn as it goes into storage. Here is updated information on products and efficacy from my recent tests in Georgia.
Actellic 5E (labeled for corn) – This is the standard product for shelled corn, but it is also the most expensive product to purchase. A full rate (12.3 oz per 1000 bu) will provide protection from weevils for at least 9 months, but reducing the rate will decrease the longevity of the protection. Actellic is susceptible to heat breakdown.
Centynal (labeled for corn and wheat) – Centynal is fairly inexpensive and will provide 3 to 6 months protection from weevils. It is critical to apply a full rate (8.5 oz per 1000 bu) or weevil control will be compromised. This material may also be used for treatment of empty bins.
Diacon (labeled for corn and wheat) – Diacon is an insect growth regulator that is effective at killing immature grain moths and beetles, except weevils. The 4 oz per 1000 bu rate is sufficient for tank mixing.
Storcide II (labeled for wheat) – Storcide II is an excellent option for stored wheat, but is not labelled for use on corn.
Malathion (labeled for wheat and corn) – This product has been widely used in the past, but is not currently recommended due to well documented resistance in many stored grain insect populations.
Tempo SC (labeled for empty bin use only) – Tempo is an excellent material for treating empty bins and elevator boots, but is not labeled for application directly to grain.
Three-way tankmix – Tests from 2015 showed that a three way tank mix of Centynal (8.5 oz) plus Diacon IGR (4 oz) plus PBO-8 Synergist (13.5 oz) will provide 6-9 months of protection from weevils. This is a moderately priced option for growers in markets where other products are unavailable or cost is a limiting factor.
Regardless of the product used, please be mindful that grain protectants are not a silver bullet. Applications should only be made to cooled grain (do not apply before sending grain through the dryer) that will be stored for more than 3 months. Apply protectants at the bottom of the auger so the kernels have a good chance to contact the insecticide while moving up to the top of the bin. Long-term grain storage also requires grain at an appropriate moisture content, proper housekeeping, use of a spreader when filling bins, and managed aeration.
Additional information is available in the 2016 Georgia Pest Management Handbook or in a recent Extension Publication (http://www.aces.edu/pubs/docs/I/IPM-0330/IPM-0330.pdf) that Dr. Kathy Flanders at Auburn University and I authored earlier this year.
It’s always long, hot day when many of us agents come together to help plant and harvest the Brooks County Silage Variety trials. I went to help them harvest a few weeks ago. County Agents Ben Shirley and Stephanie Hollifield did a great job coordinating the harvest. Ben and intern, Meghan were in the field cutting silage. Stephanie was in the weigh house taking tonnage. Lowndes County Agent Mihasha Dowdy and I were in ‘the pit’ collecting silage samples which are sent to receive milk producing capabilities. Below is the data shared by Brooks County Agent Ben Shirley on their Brooks County Ag Connection blog I wanted to pass along.
I want to share results obtained from the Brooks County 2016 Corn Silage Variety trial. We planted this trial on April 25th and harvested 14 weeks later on July 27th. This year’s trial included 69 replications, 23 varieties replicated three times each. There were no significant differences in yield among planted varieties. The varieties are ranked according to two different parameters, lbs. of milk/acre and green tons @35% moisture/acre. We conduct this trial annually, in order to assist our Dairymen and growers with variety selection and planting decisions pertaining to silage production. We would like to thank our cooperators, sponsors, and seed companies for their support and assistance. All data collected is available at (the Brooks County) office, please call or e-mail us if you would like additional copies or if you have any questions. Also, I have provided a link to view the data in its entirety.
Note* Keep in mind no significant differences were found between the varieties; ranking of varieties is from highest to lowest only.
Note* DKC67-88 only replicated 2 times, all others replicated 3 times.
Here is some corn that is now denting (R5). We are getting closer to physiological maturity. At this time, the crop is still needing water but less than before. Once the milk line progresses to the bottom of the kernel, we will see the ‘black layer’ form. We can then cut off irrigation. In the photo below, you will also notice the “milk line.” This is the separation between the softer doughy white portion close to the cob and the starchy, solid portion at the top.
When we stage kernels in R5, we look at the milk line: 1/4, 1/2, or 3/4. This is good for observing kernel development. Progression of the milk line varies due to temperature, moisture, and hybrid maturity. Here is a table from “Corn Growth & Development” that shows the expected trend:
Southern rust can still hurt us until about 1/2 milk line. We have sprayed most everything for rust right now, but there are reports of rust in many fields still. This is a good time to evaluate the control we got from gungicides. We may also look for stinkbug damage on field borders. If the ears are curved, the damage from SB was early. If individual kernels are damaged, damage from SB occurred late.
Southern corn rust has been diagnosed thanks to Extension Agents Chase Hembree (Seminole County), Andy Shirley (Mitchell County) and consultant Rome Ethredge. Here is a photo below:
We’ve sprayed some of our corn in the county already as we are two weeks into tassel. Here are some comments from UGA Extension Pathologist Dr. Bob Kemerait:
- Southern corn rust is the most important disease affecting corn in Georgia.
- Southern corn rust was found today in a very small amount in Seminole County on corn at the R2/blister stage (older than most corn in the state).
- The disease cab spread rapidly in storms and also with irrigation. Conditions last week were favorable for development and spread.
- I have recommended that growers hold off spraying until we find rust. Now that we have found it, I have enough respect for the disease to say that growers in the southwestern part of the state whose corn has reached (or is about to reach) tassel growth stage an application of fungicide to protect the crop. Growers in other areas removed from extreme SW Georgia should consider to monitor the spread of the disease. Some may want to make fungicide application either as a 1) Safeguard or because 2) they are already making a trip across the field to spray something else.
- If northern corn leaf blight is not a problem in a field, then growers have many fungicide options, to include tebuconazole to manage rust. For longer protective windows or where NCLB is also a problem, growers should apply strobilurin or fungicides that include some combination of strobilurins, triazoles, and SDHI active ingredients.
ASIAN SOYBEAN RUST
As of today, Asian soybean rust has now been found in small amounts on KUDZU in the following counties: Miller, Baker, Grady. We can assume that soybean rust is present in low amounts throughout SW Georgia.
We are starting to tassel (VT) and move into reproductive growth stage on corn (R1), when the silks emerge from the little ears and the pollen starts falling from the tassels. For Seminole Agent Rome Ethredge writes, “The greatest production of pollen from a field will occur over 4 days, with some pollen shedding for a week or more. Over 2 million pollen grains fall from each tassel. Peak pollen shed is mid morning and then towards late afternoon more falls, but if it’s raining or a heavy dew the plant won’t shed pollen until it dries. Also, some research shows that when the temperature goes above 86 degrees there isn’t much shed. If it’s cloudy and slightly cool, pollen may fall most of the day. Extreme heat (100 degrees) can kill some of the pollen.”
This is also a critical time in corn development where we don’t want stress on the plants. Stress during silking can reduce the number of kernel per ear. The number or rows will not be affected now as they were decided already. Disease is the main topic this week with corn, and here is an update from UGA Extension Pathologist Dr. Bob Kemerait on disease in CORN and SOYBEANS.
Here are a couple of notes on the current disease situation:
- Our scouts have found Asian soybean rust on kudzu in Miller County today (May 17th). This is the earliest we have found it since 2005, and it likely means rust will be problematic for our soybean producers this year. Current conditions favor spread of the disease within kudzu.
- Corn in the earliest planted fields is approaching the tassel growth stage and growers are beginning to ask questions about spraying fungicides. Here are my thoughts:
- Tassel stage (or just prior to tassel) is an appropriate time to consider applying a protective fungicide. This is especially true if a) southern corn rust has been detected in the area, b) northern corn leaf BLIGHT is problematic in a field (typically with a less-resistant hybrid), c) conditions have been favorable for disease (very wet), d) the corn was planted LATE or e) the grower is aggressive in a disease management program and wants to make sure the crop is protected.
- As of today (May 17th), we have not found SOUTHERN CORN RUST in Georgia and conditions have not been especially favorable for southern rust.
- As of today, we have had one report of common corn rust from Mitchell County. Common rust typically forms pustules on both sides of the leaf and does NOT need a fungicide application.
- As of today, I have only had a report of northern corn leaf BLIGHT from Ty Torrance in Decatur County. Northern corn leaf blight can be an important problem that requires a fungicide treatment IF it is severe (e.g., a susceptible variety and favorable weather). The NCLB in Decatur County was confined to the bottom leaves and there were only a few lesions on about one plant out of 15. The grower is right to be aware of the problem but I do not think a fungicide is needed for NCLB in that particular field.
- Northern corn leaf SPOT has been found in Mitchell County by Andy Shirley. Typically we do not spray for this disease, except in severe cases. The northern corn leaf spot in this field was confined to the lower leaves and did not appear to be spreading.
CORN: We have not detected southern corn rust in Georgia yet. Conditions over the next few days are more favorable for disease spread, but (overall) conditions have been unfavorable. I would not argue with a grower who wants to apply a fungicide at this time (to corn) as it reaches the tasseling growth stage; HOWEVER I think the grower is better advised to DELAY a fungicide application at this point and wait at least a week or so.