Current Situation: Corn crop ranges from just planted to V4. Corn has had a rough time due to the cold weather and wind over the last couple of weeks. Wheat crop ranges from early heading (Feekes 10.3) to full flowering growth stage. Field conditions are becoming dry enough to apply fertilizer, burndown herbicides as we prepare for the upcoming season.
Below is the weather summary from the UGA Weather Station at the Sunbelt Ag Expo for the period of April 8-14, 2022. The 2 inch soil temperature ranges from 60.6 to 70.2 degrees for this period of time.
Corn: The corn crop ranges from just planted to just planted to V4 and a lot of fields are struggling due to nutrient deficiency or other issues.
Dr. Dewey Lee discusses some points about the current corn situation. “Rain, cold weather frustrating corn progress” His blog post is here.
How do I take a tissue sample in corn?
Plant tissue sampling should be used in tandem with soil sampling to determine:
(1) If essential elements are presently low, adequate or excessive in the plant and;
(2) Whether the proper ratio of certain elements exists.
It is advisable to take plant tissue samples throughout the growing season to monitor nutrient status and detect any deficiencies or imbalances. If a deficiency or imbalance is detected early enough, it can usually be corrected in time to improve yield.
In corn there are 3 good opportunities to do tissue analysis.
1. Seedling stage (all of the above ground corn) 15-20 plants
2. Prior to tasselling (the first fully developed leaf just below the whorl) 15-20 leaves
3. From tasselling and shooting to silking (the entire leaf at the ear node or immediately above or below) 15-20 leaves
If you have questions about tissue or soil sampling please contact your local county agent.
Volunteer Peanut Control in Field Corn (Prostko)
Been getting a few calls about controlling volunteer peanuts in field corn. Remember that the volunteer peanuts that emerge from seeds that made it thru the winter and rains are some super tough plants. A couple of thoughts:
Roundup Ready Corn: Split applications of glyphosate at least 10 days apart. Glyphosate can be applied over-the-top of field corn up to V8 stage or 30″ whichever comes first. Drop nozzles or lay-by applicator should be used when corn is 30″ to 48″ tall.
Liberty-Link Corn: Split applications of Liberty (glufosinate) at least 7 days apart. Liberty can be applied over-the-top up to V6 stage of growth. For corn 24″ to 36″ tall, apply with drop nozzles or lay-by rig.
Conventional Corn: Split applications of dicamba @ 0.25 lb ae/A applied EPOST (8″ tall corn) + lay-by (up to 36″ tall corn). These dicamba applications must be separated by at least 14 days. An alternative treatment would be dicamba (EPOST) followed by Evik (lay-by).
**Atrazine can also be included in any of these EPOST applications as long as corn is < 12″ tall.
Wheat Stem Maggot
According to Rome Ethredge, retired County Agent, there are at least 3 reasons why we are seeing some white wheat grain heads in the field this week : insects, freeze damage, fusarium head blight. Yesterday (April 14, 2022) I noticed a few white heads in area wheat fields in Colquitt County. As it turns out it is Wheat Stem Maggot. Cody Bowling, Seminole County Agent, also reported this insect in Seminole County and he helped identify it. The bleaching head were caused by insect feeding on the stem, cutting off photosynthate and nutrient and water access to the head and it turns white. Wheat Stem maggots lay the eggs and hatch into the larva or maggot, since it’s a fly, that would feed into the stem. Wheat stem maggot feeding occurs just above a plant node and they rarely cause economic yield loss.
More on Wheat diseases
Dr. Alfredo Martinez, UGA Plant Pathology and I have been getting questions about timing of Fusarium fungicide spray and it is important to spray while the wheat is flowering which occurs not long after heading but requires checking the field. You can see the anthers coming out in the below photo from Purdue University. Dr Martinez has the fungicides and rates in the pest management handbook and these fungicides are also effective on Leaf rust as well.
Tips on Managing Seedling Disease In Cotton
I have received a question or two about managing cotton seedling disease. Below are a few points to consider from the UGA Cotton Production Guide.
Good management practices to reduce the chance of seedling disease include the following:
- Plant in warm soils where the temperature at a 4-inch depth is above 65° F and where the 5-day forecast doesn’t call for cooler or cooler/wetter weather. NOTE: Cotton growers should NOT plant cotton if at all possible when conditions are cool and wet or if the forecast calls for such conditions soon after planting, even if they plan to use additional fungicide treatments!
- Plant seed on a raised bed since soil temperatures in the bed are generally slightly warmer than surrounding soil and drainage is likely to be better. Cotton planted in conservation tillage is not grown on raised beds, thus potentially increasing the threat from seedling disease.
- Avoid planting seed too deeply. Seed that is planted too deeply results in longer periods before the young seedling cracks the soil surface, increasing the likelihood of seedling disease.
- Correct soil pH with lime (pathogenic fungi are more tolerant to acidic soils than are cotton seedlings; pH should be in the range of 6.0 to 6.5).
- Fertilize according to a soil test so as to promote rapid seedling growth; however care should be taken to avoid “burning” the seedling with excessive rates of at-plant fertilizers.
- Avoid chemical injury through the use of excessive amounts or improper application of insecticides, fungicides, or pre-plant herbicides.
- Plant only high quality seed as indicated by the percent germination in the standard seed and cool germination tests. Preferably, cool germination test results should be above 70%, though 60-69% is still adequate.
- Additional seed treatment fungicides such as Dynasty CST, Trilex advanced, and Acceleron, beyond the “base” treatment can significantly reduce the amount of seedling disease, increase stands, and potentially improve final yields where conditions are favorable for disease development. However, significant outbreaks of seedling diseases are a sporadic problem. Because we cannot reliably predict which years will have greater amounts of seedling disease, growers can become justifiably frustrated when trying to determine the economic benefit of the additional fungicide.
Peanuts: According to Bob Kemerait, UGA Plant Pathologist, the management of nematodes in peanuts includes a) variety selection, b) crop rotation, and c) selection of nematicides.
Products for management of nematodes in 2022 include:
a. Telone II (4.5-9 gal/A),
b. AgLogic (7 lb/A in-furrow),
c. Velum Total (18 fl oz/A in-furrow)
d. Velum (6.5 to 6.84 fl oz/A in-furrow)
e. Propulse (13.6 fl oz/A pegging-time) Note: also effective for control of
white mold and leaf spot
f. Vydate CLV (for directions on in-furrow and foliar applications, see
label)
g. Return XL (for application information, see label)
Lesion nematodes are an emerging problem on peanuts in some areas, especially when high numbers are present in a field and damage occurs to the pegs. Research continues; however use of Propulse or perhaps, Vydate-CLV at pegging time is likely to be an important management tool.
What about Aspergillus crown rot? I am glad you asked. Bob mentions that Aspergillus crown rot is an important seedling disease, especially when conditions are hot and dry at planting, or when seed-quality
is a concern. Farmer-saved-seed is often at greatest risk.
To manage Aspergillus crown rot,
a. Ensure quality of seed
b. Ensure effective fungicide seed treatment with excellent seed coverage
c. In 2022, Rancona will likely be the predominant fungicide seed treatment for peanut
d. Use in-furrow products such as Velum and Proline. Note that azoxystrobin products (Abound, etc.) have been widely used as in-furrow treatments in peanut, but are less effective against Aspergillus crown rot now than in the past
e. Manage insects such as Lesser Cornstalk Borers
f. Avoid planting into hot and dry soils
g. Irrigate to cool hot soils.
What else did you do this week?
This week was interesting. We planted several corn plots first part of the week. Two at the Sunbelt Ag Expo and one on farm. A herbicide study evaluating nutsedge control in a newly sprigged hay was established this week. Simmer Virk, UGA Precision Ag Specialist, was in town to evaluate one of the very first planters in Georgia with Precision Planting’s SmartDepth control system which is at the Sunbelt Ag Expo.
If you have questions please contact your local County Extension agent.