Figure 1. July 14th driving route for crop condition report
USDA-NASS general crop conditions categories are defined as followed:
- Very Poor – Extreme loss of yield potential; complete or near complete crop failure.
- Poor – Heavy loss of yield potential due to excessive soil moisture, drought, disease, etc.
- Fair – Less than normal crop conditions. Yield loss is a possibility, but is not severe.
- Good – Yield prospects are normal or better. Moisture levels are adequate with minimal disease and insect damage.
- Excellent – Yield prospects are above normal and crops are experiencing little, if any, stress.
Platte River Valley (Fremont, Ames, North Bend)
Overall, corn is in poor to good condition and soybeans in fair to good condition. Corn is pollinating and in some cases done and in the blister stage, R2 (link to corn growth stages). The ‘shake’ test for pollination success looks good (Figure 2). About 70% of the corn fields were pollinating. Gray leaf spot (GLS) is still at low incidence and severity in the field I noticed with GLS last week near Fremont (Figure 3). One corn field showed a noticeable infection of Goss’s Bacterial Wilt on the upper leaves (Figure 4), which is likely due to a more susceptible hybrid as conditions for infection (hail/wind damage causing wounds) have been good. Soybeans that were planted in early May are at the beginning pod growth stage, R3. Detasseling season is in full swing this week (Figure 5) and some irrigating of seed corn and commercial corn was being done. Soil moisture sensors, rain and ET gauges are useful tools to improve scheduling irrigation that some growers installed this season (Figure 6). For more information on tools for improving the use of groundwater resources visit the Nebraska Agricultural Water Management Network.
Figure 2. Shake test for successful corn pollination on corn just reaching the blister stage, R2.
Figure 3. Low incidence and severity of gray leaf spot still this week.
Figure 4. Goss’s bacterial wilt lesion likely on a susceptible hybrid. This disease is best managed through using resistant hybrids.
Figure 5. Seed corn field being detasseled.
Figure 6. Rain gauge and soil moisture sensors used for fine-tuning irrigation.
Central Upland Flats and Maple Creek (Located north and south of the Maple Creek along the Webster Rd and Co Rd N)
Corn is in fair to excellent condition and soybeans in good to excellent condition. 70% of the corn fields south of the Maple Creek are in the silking stage (Figure 7). Soil moisture is adequate and temperatures have been ideal for pollination. I did find some common rust pustules, but no gray leaf spot even on corn after corn acres (Figure 8). Most soybeans are in the full bloom stage to beginning pod stage and about 1 to 2 ft tall (Figure 9). A few acres of sorghum (Figure 10) have been planted this season. Interesting fact, sorghum is not attacked by corn rootworm nor is it an alternative host. Some irrigation had or was occurring (Figure 11), but by and large most pivots were sitting.
Figure 7. Most fields pollinating as this one is in this region of the county.
Figure 8. Little or no leaf disease on corn after corn near the Scribner Airbase.
Figure 9. Soybeans 2 ft tall and setting pods.
Figure 10. Small field of sorghum or milo.
Figure 11. Pivot irrigation on field corn.
Elkhorn River Bottom (Scribner, Hooper, Winslow, Nickerson)
Corn and soybean conditions ranged from poor to good with lots of variability across the fields. Northern corn leaf blight was found in a field (Figure 12) near Nickerson. Corn hybrids vary in their susceptibility to this fungal disease, so check with your corn seed representative to prioritize fields to scout. Nitrogen deficiency symptoms were evident across the county at different levels of severity. Key visual symptoms of nitrogen deficiency is yellowing or chlorosis of lower leaves in a V shaped pattern (Figure 13) Soybeans nodulation looked good (Figure 14) in soybean fields I checked (active when pink-colored fluid leaks out when nodule broken).
Figure 12. Northern corn leaf blight. Hybrids do differ in susceptibility to this fungal disease.
Figure 13. Corn nitrogen deficiency.
Figure 14. Nodules formed on soybean roots from symbiotic relationship with Bradyrhizobium japonicum (a bacteria). This fixes nitrogen for the plant.
Northwest Rolling Hills/Pebble Creek (Snyder, Dodge)
The crops in are fair to excellent condition. Corn is only about 10% pollinated in this region, noticeably later than corn in the southern half of the county. Some late-season nitrogen applications were made to corns fields (Figure 15). For the Soybean Management Field Days location south of Snyder, soybean were setting pods, R3, and corn was just starting to silk, R1. Crop water use from July 7 to July 14 was 1.21” corn and 1.20” for soybeans. As of July 16th, soil watermark sensors (Figure 16) showed a 0.7, 0.4, and 0.2 inch depletion from field capacity for the 1, 2, and 3 ft depth, respectively. Considering the time it takes for irrigation preparation and to irrigate the entire field, irrigation should be started when soils reach 65% percent of field capacity or 35% depletion to avoid crop stress. We have not reached this trigger point for irrigation yet at this location for soybeans.
I have noticed some significant potato leaf hopper injury to alfalfa stands (Figure 17). Potato leafhoppers have the potential to cause economic injury every year in Nebraska usually to second and third cuttings. The 1/8 inch long, bright green, wedge-shaped insect cause’s injury by injecting a toxin into the plant as they feed. Treatment decisions are based on the numbers captured by a sweep net and you do not need very many to cause a problem. Early second cutting can be the best management option. For more information on potato leafhopper treatments click here.
Figure 15. Late-season nitrogen (N) applied with a highboy to areas of this field with N deficiency.
Figure 16. Soil moisture sensor for irrigated soybean treatments at Snyder for the Soybean Mgt. Field Day.
Figure 17. Damage caused to a new seeded alfalfa field from the toxin injected into the plant by the potato leafhopper.
North-central Sand Dunes/Cuming Creek (North of Scribner by Lone Tree and Dead Timber)
The crops are in poor to fair condition in this area. Sulfur deficiency in corn was visible in some portions of fields in this region. Interveinal chlorosis of the upper corn leaves (Figure 18) occurs since sulfur is not very mobile in the plant (bottom part of plant is more green), unlike nitrogen that plants re-mobilize from lower leaves to the upper leaves (bottom part of plant yellow if nitrogen). Late-season applications of sulfur may still be a viable option. If you are interested in conducting on-farm research (did it work and did I make money?) related to sulfur fertilization for corn, please contact me.
Figure 18. Sulfur deficiency in corn on Thurman loamy fine sands.
Northeast Rolling Hills/Logan and Clark Creek (Uehling)
Overall, crop conditions were very poor to fair. Replanted corn has reached the V9 growth stage (Figure 19) and soybeans the V4 growth stage. Late-emerging waterhemp has become a problem in some fields (Figure 20). A herbicide program to address added waterhemp pressure next year will be needed. There are several post-emergence herbicide options that provide residual control in soybeans (Figure 21). The cool weather is not ideal for replanted corn. However, on Monday we were slightly ahead on growing degree days since May 1. The new U2U corn growing degree day tool can be used to track heat units for your area on replanted corn compared to average and recent years.
Figure 19. Replanted corn at V9 in this field west of Uehling.
Figure 20. Late emerging waterhemp in hail-damaged fields will be an issue this year and next year with all the seed produced.
Figure 21. Soybean herbicide options with residual to help next season when all this waterhemp goes to seed.
Agronomic matters for this next week
- Scout corn for leaf fungal diseases to assess need for fungicide applications. Contact your seed rep to make a list of which hybrids are more susceptible and may benefit most for foliar fungicides.
- Potato leafhopper scouting and early cutting decision.
- Monitor or assess soil moisture prior to irrigation with soil probe or read soil moisture sensors.
Check in next week for the July 21th crop report for Dodge County.
[…] condition (Figure 3). Last year at this time, more acres were in very poor to poor condition (July 14, 2014 Crop Report). The growth and development of corn ranged from V10 (10 visible collars) on replanted corn to late […]
[…] previous mid-July crop tours from July 14 and July 21, 2014 and July 16, […]