Crop Report May 3-17

 

 

 

Weather conditions

In past two weeks, SW Nebraska received about 1 inch of precipitation, average air temperatures raged between 45 F and 65 F generating 123 GDD (growing degree days), soil temperatures had a gradual increase from 50 F and currently are at 58-62 F.

Corn planting and emergence progress

Picture 1. Emerged corn looks yellow in SW Nebraska
Emerged corn looks yellow due to lack of sunshine and cool temperatures

Most of the farmers are finishing up corn planting. There is about 20% corn acres yet to be planted and roughly 20% already emerged. Early planted corn emerged well despite the low soil temperatures. Strips that were tilled for corn to be planted consistently had higher reading then data from the weather stations, thus no injury occurred in most places. Corn plants, however, do look pale and yellow in color due to lack of sunshine and temperatures, but will grow out of it with warmer weather to come (Picture 1). To asses corn replant options due to poor emergence click here.

Wheat

Wheat is generally in good conditions and is pushing flag leaf. There are reports of isolated stripe rust infections in SW Nebraska and preventive areal fungicide applications started this week (Picture 2). Applications prior to flag leaf emergence are not advised. If farmer has a stripe rust resistant variety, regular scouting and prolonging fungicide application by 10 days or so may provide long enough residual activity of fungicide to protect the flag leaf and avoid second fungicide application later on in the season.

Wheat is showing signs of nitrogen deficiency. Yellowing of the leaves is common in low areas of the fields with standing water and poor drainage conditions. In addition, sporadic yellow spots may be found throughout the field due to nitrogen that has been leached bellow the root zone (Picture 3).

Picture 3a. Nitrogen deficiency in wheat
Picture 3. Nitrogen deficiency in wheat

Picture 3b. Nitrogen defficient wheat leaves

Field peas

Field peas are relatively new crop in western Nebraska with promising agronomic potential and growing national and international markets. UNL Extension partnered with 5 farmers to receive USDA SARE (Sustainable Agriculture and Research Education) grant and investigate agronomic issues related to field pes production in SW Nebraska. Weed control is one of those issues and it will be interesting to see how well field peas compete against kochia (Picture 3). Field peas are at 3-5 leaf stages. For more information on field peas click here.

Picture 4. Field peas at V3 competting with kochia
Picture 4. Kochia infested field peas field
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Crop report June 10

Srpayer stuck in the muddy field
Sprayer stuck in the muddy field

Weather conditions

Less than 0.5 inch of precipitation in past 7 days have dried fields enough for farmers to continue planting and spraying weeds. Assess wetness of your field carefully!!! Planting in wet soils can cause severe crusting and problems with crop emergence, especially in soybean. Avoid spraying wet areas with heavy equipment. Mark them with flag and spot-spray with ATV  sprayer.

Water management

Irrigating wheat is recommended to keep up with the water demand. On the 85-90 F days we had on 06-09-2015 wheat uses 0.37 inches per day, which is 2.59 per week. Wheat extracts water from top 3 foot, which means that you need approximately 0.9 inches/foot/week to meet the wheat water requirements. Most of our silt loam soils can hold 0.7 inches/foot at field capacity, which means that wheat will start showing water stress at 0.35 inches/foot (50% depletion). In other words, irrigators on a typical soil in SW Nebraska have an irrigation management span of 1 inch (in top 3 foot) to avoid water stress.

In summary, you will need 2.59 inches on demand side and available soil moisture + rain + irrigation on the supply side of equation. Frequent irrigations at 0.5 inches irrigation depth are typically recommended to allow water infiltration and avoid runoff. Probe or use soil moisture sensors to estimate what you already have in the soil get you in the ballpark.

Wheat

Wheat is at flowering stage. Hail damage observed in west Chase County. Stripe rust is moving north and is now observed in Perkins and Keith Counties. Fusarium head blight (head scab) has not been observed jet, but treating your wheat with Caramba and/or Prosaro is recommended to keep flag leaf protected from disease. Check Nebraska Extension article on “Distinguishing between head disorders of wheat” to correctly identify head scab.

Hail damage (1st and 2nd picture), stripe rust and Black chaff on whaeat in SW Nebraska
Hail damage in Chase Co (first 2 pictures), stripe rust (3rd picture) and Black chaff (4th picture) in Perkins Co

Black Chaff is a seed-borne bacterial disease that started showing up in fields where bin-run seed of susceptible varieties has been planted last fall. No treatment is recommended to control Black Chaff; planting tolerant variety and certified, pathogen-free seed are the best strategies to prevent yield losses caused by Black Chaff.

Seedling disease in corn
Seedling disease in corn

Corn

Corn growth stages range from emergence to V4. Soil borne diseases have been observed in SW Nebraska; popcorn seems to be more susceptible then field corn. Assess your field carefully for stand reduction before making decisions on replanting. Economic threshold for replanting irrigated corn planted at 32,000 seeds/ac is about 20,000 seeds/ac (about 45% in stand reduction). As fields are drying out we see more applicators spraying weeds that have been growing wild in past couple weeks. Amaranth spp. (pigweed species) started emerging.

Flowering canopies of field peas (1st pic), potatoes (2nd pic) and wheat (3rd pic). Once you see potato flower you will never forget it!
Flowering canopies of field peas (1st pic), potatoes (2nd pic) and wheat (3rd pic). Once you see potato flower you will never forget it!

Other crops

Soybean are cracking and planting is about 55% done. Planting in wet conditions can cause crusting in some areas. If crusting about

Crop report June 2

Farmers in SW Nebraska are struggling to make timely herbicide applications in muddy fields
Farmers in SW Nebraska are struggling to make timely herbicide applications in muddy fields

Wet conditions in SW Nebraska continue to interfere with timely panting and spraying operations.

Stripe rust on wheat in Chase County 6
Stripe rust on wheat in Chase County
Areal fungicide applications on stripe rust infected wheat 1
Areal fungicide applications on stripe rust infected wheat

Wheat

Wheat started flowering and it is in good condition, with the exception of stripe rust being severe in some areas of Chase County. Time to look at disease tolerance characteristics of variety being planted last fall and consider preventive and curative fungicide applications to avoid catastrophic yield losses. Rain has also increased our risk for Fusarium Head Blight. Therefore, products that work well on both stripe rust and head scab such as Caramba and Prosaro can be used while wheat is at flowering stage.

Iron deficiency in corn on high pH soils 1
Iron deficiency symptoms on corn due to high soil pH
Pea size hail damage in V3 field corn
Pea size hail damage on V3 corn. Crusting observed after corn emergence.

Corn

Corn planting is 90% done, but V3-V4 corn is also commonly found in the area. Fields show signs of farmers struggling to make timely herbicide applications. Areal herbicide application is recommended if weeds are growing out of optimal control time. In the west parts of Perkins and Chase Counties pea size hail damage is observed in corn. Research has shown that hail injury on V2 corn will not cause yield losses.

Field peas

Field peas are at V5-V9. In some fields peas look chlorotic. Symptoms are expressed most probably due to lack of sunshine and limitations of micronutrients in high pH soil. Peas should be getting plenty of nitrogen through nitrogen-fixing bacteria present in nodules. Farmers that applied inoculum should not be concerned about nodulation. Test the activity of nodules by cutting them in half. If they are red they are active! Drastic differences in conditions are observed between field pea varieties.

Varietal differences in field peas
Varietal differences in field peas
Well nodulated field peas look chlorotic due to lack of sunlight and nutrient deficiency in high pH soils
Well nodulated field peas look chlorotic due to lack of sunlight and nutrient deficiency in high pH soils

 

Other crops

Soybean planting is still in progress (about 35% done). Grain sorghum planting about 30% done.