Southeast Minnesota is excited to have Josh Shofner join
the agronomy team. Josh spent the past two years as an
Account Ma...
SCN race shifts and high cyst counts are an added
stress to soybean fields. Planting SCN-resistant soy-
bean varieties tha...
Extreme, early-season moisture, strong wind events and
corn rootworm feeding all contribute to increased poten-
tial of co...
KC Lensing, Buck, Shofner
DuPont Pioneer
Sales & Marketing
PO Box 466
Johnston, IA 50131
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Eastern MN Walking Your Fields newsletter-July


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This July issue of Walking Your Fields newsletter contains articles about: soybean pests and diseases, the benefits of cover crops and the causes of corn root lodging.

Articles are written by DuPont Pioneer agronomists in southeastern Minnesota and are distributed on behalf of DuPont Pioneer account managers and Pioneer sales reps.

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Eastern MN Walking Your Fields newsletter-July

  1. 1. Southeast Minnesota is excited to have Josh Shofner join the agronomy team. Josh spent the past two years as an Account Manger for DuPont Pioneer in SE Minnesota. His new role as Field Agronomist replaces Ryan Bates who accepted the Field Agronomist position with Pioneer in Western Wisconsin. Soybean aphids are right on schedule and were recently reported in southern Minnesota. Even if you planted soy- bean seeds treated with a nicotinoid insecticide to delay aphid population establishment, you will still want to scout your fields for this pest from V5 through R5. The soybean aphid overwinters in buckthorn and mi- grates to legumes (soybeans, alfalfa and clovers) in July. It’s less than 1 mm in length but when left untreated, eco- nomic infestations can reduce yields by more than 10 bushels/acre. Symptoms. Aphid-infested soybean plants may look sim- ilar to a potassium deficiency: curled leaves, often yellow on the outside. Aphids produce a sugary excrement, known as honeydew, on leaves, which promotes soot mold growth and can serve as a feeding ground for ants. Plants infested by the soybean aphid will also appear shorter. Besides a stunted plant with noticeable discoloration, you can also detect these oval-shaped, light green pests with black ―tail pipes‖ near the end of the abdo- men by doing numer- ous sweeps through the field. Take Action. Count the number of aphids on 30 to 50 plants throughout the entire field and calculate the average number of aphids per plant. If aphid populations reach 250 per plant and are increasing dur- ing the R1 – R5 growth stages, consider a foli- ar insecticide to control the population. Your local Pioneer sales rep can help with product recommendations. There are also several beneficial insects that feed on soybean aphids and can naturally control the aphid population. They include Asian lady beetles, damsel bugs, green lacewing larvae, and insidious flower bugs. White Mold (Sclerotinia Rot) - Sclerotinia white mold is favored by cooler night temperatures (50-60°F) and moist conditions in the plant canopy. In addition to cool temper- atures, the production of white mold apothecia (mushroom-like structures) requires moist soil and a closed canopy. If surface soil moisture is low or the soy- bean canopy is not closed during flowering, the fungus would not be able to produce apothecia. When scouting for this disease, pay attention to the fields that had white mold previously and that have good soil moisture and a closed canopy. The first evidence of white mold is a chlorotic, girdling lesion covered with white, fluffy mycelium at one of the middle nodes. The evi- dence of the disease be- comes conspicuous in August when dead tops start to show up in fields. White mold is a disease of high management. It is most likely to show up in low spots of the field, where plant populations are high, in narrow rows, in tightly closed canopies, where plants become lodged and/or where less tolerant varieties are planted. WALKING YOUR FIELDS® newsletter is brought to you by your local account manager for DuPont Pioneer. It is sent to customers throughout the growing season, courtesy of your Pioneer sales professional. The DuPont Oval Logo is a registered trademark of DuPont. PIONEER® brand products are provided subject to the terms and conditions of purchase which are part of the labeling and purchase documents. ®, TM, SM Trademarks and service marks of Pioneer. © 2013 PHII. New Team Member WALKING YOUR FIELDS ® July 24, 2013 - Issue 4 Photo by Josh Shofner and Brian Buck 7/5/13 Photo:DuPontPioneer Soybean plant showing symptoms of white mold. Soybean Aphids White Mold (Sclerotina Rot) Photo: Marty Lovrien Soybean aphids and an ant on under- side of soybean leaf. Aphids excrete ―honeydew,‖ a sugary substance that attracts other insects and also results in development of sooty mold.
  2. 2. SCN race shifts and high cyst counts are an added stress to soybean fields. Planting SCN-resistant soy- bean varieties that include the Peking and PI88788 source of resistance, along with rotating to a non-host crop are two of the best ways to prevent SCN infesta- tions. Extension specialists have advised that overuse of any single source of SCN resistance can lead to SCN race shifts over time. Therefore, it is important to switch between varieties and always scout fields. To scout for SCN, dig up soybean roots and gently wash the soil away. If you don’t see a high number of SCN, recheck in two weeks to make sure you are not between production cycles. DuPont Pioneer offers both the Peking and the PI88788 source of resistance. Take time to dig and compare the female cysts numbers between the Peking and PI88788 sources. When SCN becomes prevalent, it also promotes the de- velopment and spread of Sudden Death Syndrome and increases the severity of Brown Stem Rot. Below are recommendations from the Plant Health Initia- tive funded by the Soybean Checkoff on crop and soy- bean resistant variety rotation:  Rotate with non-host crops to reduce SCN numbers.  Rotate with resistant soybean varieties to reduce yield loss due to SCN.  Rotate the resistant varieties you use: don’t use the same one twice in a row.  Rotate with tolerant or susceptible soybean varieties only if SCN numbers are low. More information about SCN resistant varieties and SCN damage is available through you local Pioneer sales rep and also available in the Soybean Cyst Nematode Man- agement Guide: SCNGuide_5thEd.pdf A quick trip across southern Minnesota countryside re- veals that many growers are in the same boat this year with flooded land and partially or completely unplanted fields. When possible, these growers should consider a cover crop instead of letting fields sit fallow all season. Significant damage can be done to the soil’s biological properties by leaving unplanted fields bare, fallow, during the growing season. Research indicates that the effects of a bare field carryover into the next growing season with phosphorus (P) deficiencies and ultimately could decrease yield, especially in corn. Fallow syndrome, as this condition is known, occurs when planted fields flood or fields are left unplanted. Crops planted on that ground the following year may show signs of P and zinc (Zn) de- ficiencies, severe stunting, uneven emergence, irregular stands, purple or light green colored leaves and poorly developed roots. When no vegetation is planted, there is a reduction of soil vesicular-arbuscular mycorrhizae (VAM) fungi. VAM fungi are found around plant roots and help in the uptake of nutrients from the soil, along with increasing the plant’s tolerance to heat and drought. The fungi can be hundreds of times longer than plant roots and significantly extend the absorption zone of the root system. VAM fungi need host plants to complete their life cycle and without a growing crop during the season, the fungi will not be pre- sent for the following growing season. Cover crops have numerous benefits to the soil:  Prevent Soil Erosion  Soil Structure Improvement  Nutrient Storage  Water Infiltration Soybean Cyst Nematodes Why Cover Crops on PP Acres Photo: DuPont Pioneer Female cysts of SCN on plant roots.
  3. 3. Extreme, early-season moisture, strong wind events and corn rootworm feeding all contribute to increased poten- tial of corn root lodging. If root lodging has occurred, take time to assess the cause of lodging—don’t just assume it is rootworm feeding. Causes of Root Lodging in Corn  Wet conditions at planting, causing sidewall compaction and restricting root growth  Wet conditions early in the growing season  Strong wind and rain events during critical root develop- ment and prior to brace root formation  Reduced root growth due to nitrogen deficiency  Hybrid differences in root formation  Corn rootworm (CRW) feeding Yield loss and lodging due to CRW feeding is affected by the timing of root feeding, weather, soil type and hybrid type. Extreme root lodging often results from root feeding by CRW larvae in June, followed by summer storms. Once rootworm larvae have damaged or destroyed roots near the soil surface, they work their way down the root system. The later the root lodging occurs in the growing season, the less able corn is to straighten up without pro- nounced goose-necking. Closely monitor root lodged fields and consider harvesting at higher moistures, if stalk rot becomes an issue. Once corn hits pollination it takes about 55-60 days to reach physiological maturity. Most 100-105 day CRM hybrids pollinate around 1250-1300 GDDs. An 80 day hybrid would be around 1000 GDDs. We have had the heat needed to keep the crop going up to this point and the forecast also looks good! For example, if we average highs in the low 80s, say 82, and lows in the low 60s, say 62, the average GDUs collected per day would be 22. Doing the math below based on when you planted we should be pollinating at a reasonable date for much of the corn planted throughout SE Minnesota! Pioneer® Field360™ Select software is an interactive, web- based subscription service that combines your field data with real-time agronomic and weather information.  Track field by field Precipitation and GDUs  Scouting 101 with GPS located as-planted products  On-The-Go organized field applied data Pioneer Field360 Notes pinpoints your field location via satellite imagery so you can record notes or photos on the spot.  Displays field boundaries for Pioneer customers  Easy to use interface; available for iOS and Android™  Instantly map and organize data with notes and photos  Share data from the field via email Contact your local Pioneer Professional for more Info! Root Lodging in Corn Corn GDU Update Photo: Marlin E. Rice Corn rootworm damage reduces a plant’s structural support and makes it more susceptible to lodging. CRW injury to nonBt corn roots on left compared to Bt hybrid on the right. Taken from an Iowa State University research plot.