AGRIS Co-operative and Wanstead Farmers Co-operative

Transcription

1 Brought to you by AGRIS Co-operative and Wanstead Farmers Co-operative Volume No.3, Issue Number 8, March 28, 2011 Spring Agronomy Updates *Articles Courtesy of GROWMARK Agronomy Services PREPARE TO BATTLE SOYBEAN WHITE MOLD In 2009, weather and environment conspired to create one of the worst soybean white mold years ever witnessed in the Midwest. That white mold epidemic resulted in production of countless sclerotia, the white mold seed structure. For growers who maintain a corn-soybean rotation, many of the same fields will be back in soybeans and again potentially subject to high white mold levels. The highest levels of white mold infection and damage tend to occur in our most productive soybean fields. This is because these fields often produce robust plants that shade the ground earlier. The moist environment created within these dense soybean stands is more conducive for apothecia development and infection. Apothecia are the mushroom-like structures that project spores into the air. AGRIS White Mold Apothecia If 2011 proves to have a dry growing season, all white mold bets are off. But if a moist environment persists during the soybean bloom period, we could see very high white mold infections in many soybean fields again this year. So, what can we do to protect the soybean crop and manage white mold? Call your local AGRIS Co-operative or Wanstead Farmers Co-operative crop sales specialist for the best recommendations.

2 INSECT WINTER SURVIVAL Winter weather has been on the minds of many people lately. A common question that often starts to pop up at this time of year is: What is this weather doing to the insects and plant diseases? The short answer is: Not much, but it s actually a little more complicated than that. Insects have many strategies for avoiding lethal effects of cold temperatures. Prediction of overwintering success of field crop pests is extremely difficult because of the large number of variables involved with these strategies. Following are some brief, general comments and observations concerning pest insect overwintering. Migration Some insects are poorly equipped to withstand winter cold temperatures, so they avoid the cold by migrating to warmer areas. Black cutworm, fall armyworm, true armyworm, and potato leafhopper are all migrants. Shelter A number of our native insect species survive winter s cold by seeking adequate shelter. This usually means fencerows and woodlots, or more commonly within or under crop residue. Corn flea beetles and bean leaf beetles are in this group. Some insects use the depths of the soil to obtain winter shelter. White grubs, wireworms and grape colaspis all seek protection in the depths of the soil. Corn rootworm beetles will deposit eggs from 2 to 18 inches deep, or more, in the soil. Japanese Beetle Grub in Cell in Soil AGRIS Developmental Stage Many insects overwinter in the developmental stage that is most tolerant of winter conditions. Corn rootworms, soybean aphids, several grasshopper species, and some alfalfa weevils overwinter as eggs. White grubs and some cutworm larvae overwinter deep in the soil. Certain insects, like European corn borer larvae, can only overwinter as 5 th instar larvae. Most Midwestern pest insects are well adapted to our winters. They utilize one or more of the above strategies to avoid cold weather mortality. Barring very unusual winter weather conditions, it s usually best to not discount the insects well evolved survival capabilities. Your AGRIS Co-operative or Wanstead Farmers Co-operative crop sales specialist can help identify and recommend treatment of any insect pests in your fields. Brought to you by AGRIS Co-operative and Wanstead Farmers Co-operative Page 2

3 PROSPECTS FOR WINTER WHEAT SURVIVAL Snow and Ice Cover Snow cover on wheat can be very positive if it simply serves as a blanket that insulates against sharp temperature swings. Ice is almost invariably hard on wheat, particularly where dense sheets form. Wheat will smother under an ice sheet that remains for several days. Seeding Depth and Winter Survival Wheat should be planted in a firm seedbed at a depth between ½ and 1 ½ inches. Wheat that is planted too shallow tends to be more subject to winter heaving or cold injury. Plant Population and Productivity Healthy wheat stands usually have between 30 and 35 plants per square foot. Uniform stands having 20 to 25 plants per square foot will often produce acceptable results, especially if numerous tillers are formed. Be aware that late germinating wheat is less likely to have good tiller development, so any injury to the main stem will have a proportionately greater impact on yield. MANAGING CORN NEMATODES Managing corn nematodes has never been easy or straightforward. Effective corn nematode management requires a holistic approach where all facets of the system are examined and managed toward the goal of long term optimization of economic corn production. Where corn nematodes are suspected to be at damaging levels, the place to start is with soil samples to determine nematode species and population levels. Management efforts should include crop rotation to non-susceptible host crops, tillage (where appropriate), optimum-to-high fertility levels. AGRIS WHEN SHOULD WE APPLY RESIDUAL HERBICIDES? We have been discussing and positioning the need for residual herbicides in corn and soybeans throughout the fall and winter. Now that the season is just around the corner, the key question is: When is the best time to apply residual herbicides? Ideally, residual herbicides perform more consistently, and with minimal risk of crop injury, when applied 5 to 10 days prior to planting. This allows time for the herbicides to receive an activating rainfall. An activating rainfall is critical with residual herbicides. Rainfall will ensure optimum weed control as well as diluting any herbicide hot zones that could possibly lead to crop injury. Brought to you by AGRIS Co-operative and Wanstead Farmers Co-operative Page 3

4 However, any time an application is made several days before the intended planting date, careful planning and observation must take place. For example, if the application was made 10 days prior to the intended planting date, AND wet weather then delays planting by another 10 days, chances are that the herbicide may only provide optimum residual activity for another days. Remember, in most cases we are applying only ½ - ¾ of the full residual rate. Experience has shown that, at these rates, we can expect approximately 4 to 8 (?) weeks of residual weed control. The length of the residual activity depends on the individual herbicide active ingredient(s), use rates, amount of rainfall, etc SOYBEAN APHID AND SPIDER MITE POSSIBILITIES FOR 2011 Soybean Aphids Generally low fall suction trap counts in 2010 suggest that aphid movement to buckthorn overwintering sites was limited. In the past, these low fall suction trap counts have been well correlated with low populations in soybeans the following year. This means that we should expect generally low occurrence of soybean aphids in 2011, but that isolated populations may show up in soybeans especially near known overwintering areas. Two-Spotted Spider Mites Outbreaks of spider mites in soybeans have not bothered us for a few years now. If the current La Nina event continues into summer, hot, dry conditions could develop. We suggest that you be watchful for early signs of spider mite infestations. Problem areas could include fields with late burn-down of henbit, purple deadnettle, and chickweed. Unusually warm and dry weather will favor spider mite populations. MONITORING BLACK CUTWORM MOTH ARRIVAL A very few black cutworm moths may successfully overwinter in the corn belt, but most migrate into the area by hitching a ride on southern storm fronts or on stiff southerly breezes. The moths are weak migrants in their own right, but can hover or remain suspended in the updrafts of storm fronts for many hours. As wind currents shift, or the moths tire, they sprinkle out of these weather systems. The distribution pattern of the arriving black cutworm moths is random. This is why the pheromone traps offer useful information, specific to the individual field or local area. Black cutworm wing traps should be hung near the fields of concern, and away from bright lights, which may compete with the pheromone attractant. AGRIS Active Wing Style Pheromone Trap Brought to you by AGRIS Co-operative and Wanstead Farmers Co-operative Page 4

5 Once the first black cutworm moths are noted in the traps, the traps should then be checked a minimum of twice per week. When at least 9 moths ( 8 is used in some states) are caught over a 2 day period, this is referred to as a significant event. Earliest cutting of corn by black cutworms can be predicted on the basis of the occurrence of this significant event. Your AGRIS Co-operative or Wanstead Farmers Co-operative crop sales specialist can help with moth counts, cutworm size and recommend treatments if or when necessary. AGRIS 2011 GROWMARK, Inc., AGRIS, Wanstead Farmers The information provided in this letter is general in nature and specific information should be obtained by review of product labels and consultation with the manufacturer. Such information can be materially affected by inaccurate data or assumptions, varying circumstances, known or unknown risks and uncertainties, and many other factors which are beyond the control of GROWMARK, Inc., AGRIS, Wanstead Farmers and results can vary widely. The user will not rely on any information provided herein and GROWMARK, Inc., AGRIS and Wanstead Farmers Ltd. will not be liable for any reliance on that information. The FS logo is a registered trademark of GROWMARK Inc. and all trademarks contained herein are the intellectual property of their respective owners. Reproduction or copies of Crop Solutions that Work, in whole or in part is strictly prohibited, except with written permission from AGRIS or Wanstead Farmers. Brought to you by AGRIS Co-operative and Wanstead Farmers Co-operative Page 5