WEEKLY UPDATES

Crop Report May 13, 2009
Posted on May 14, 2009 at 15:38:57  
Ontario Field Crop Report
May 14th, 2009
by OMAFRA Field Crop Specialists

For emerging issues, questions or to provide feedback on this report, contact the CropLine at 1-888-449-0937. Technical information can also be obtained at the OMAFRA Field Crops Webpage at www.ontario.ca/crops and Crop Pest Ontario at www.omafra.gov.on.ca/croppest/. Referenced OMAFRA Publications include Publication 811 Agronomy Guide for Field Crops ($20), 812 Field Crop Protection Guide ($15), 75 Guide to Weed Control ($15), and 505 Ontario Weeds ($15). These can be obtained from your OMAFRA Resource Centre, or by calling 1-800-668-9938.

Corn:

Corn planting progressed at a reasonable pace over the last week (May 6-13) with some exceptions in the areas where heavier soils continued to dry slowly or where rainfall amounts were higher. The estimate of the province’s intended corn acreage planted to date is 60%.
In some areas pounding rains have resulted in soils that are quite consolidated. After the corn has emerged and soils have dried it may be advisable to inter-row cultivate or conduct some sort of tillage to increase the porosity of these soils.
Producers are advised to continue to plant full season hybrids until May 20th before switching to shorter season options.


Winter Cereals:
Winter cereals continue to advance, with most fields now at the stem elongation stage (GS 30 to 37). Much of the wheat crop has “snapped”, now showing good growth and good colour. Replant decisions continue to occur in fields with many bare patches, or where wet soils have prevented the crop from any significant development. Estimates now are at 10 to 12% of the crop replanted, leaving about 340,000 ha (840,000 acres) of wheat that will go to harvest. 40% of this acreage is estimated in only fair condition, with reduced yield potential in these fields. Trend line yields appear to be a very lofty target this year.
There are many reports of yellow spots in wheat fields across south western Ontario. Symptoms show up as bright yellow patches or variable strips in the field. These are the result of suboptimal nutrient availability, causing a lack of chlorophyll development in new growth. Symptoms appear most consistent with iron deficiency (Fe), but may also be manganese deficiency (Mn). Both of these deficiencies are seen on new growth and are more common on high pH soils. Limited root growth due to cold wet soils has accentuated the symptoms. Results of tests underway will be reported as soon as they become available. Unless fields are traditionally prone to Mn deficiency, symptoms should be transient and will disappear with warmer, drier conditions. Yield impact should be minimal.
Weed control is underway as conditions permit. Frosty nights (below 0 C) stopped many sprayers from May 10 to May 12. Fields that were sprayed under these conditions are showing typical “scorch” injury, which is actually surfactant burn. Yield implications of this injury is often minimal, although injury of this nature associated with the hotter hormonal herbicides can result in significant yield loss. Visual dandelion blooms and winter annuals bolting above the wheat crop show that fall burndown should be practised more often for control of these weeks. Control of these weeds at this late stage is simply “revenge” spraying, as yield impacts have already occurred.
Disease pressure remains minimal, with low levels of powdery mildew and septoria reported. Cereal leaf beetle (CLB) has been reported at high levels in Michigan and Ohio. Norfolk County is a traditional hot spot for CLB, with initial reports of adult beetles and 1st instar larvae. SCOUT! Adult and larvae descriptions and pictures can be found in the new Agronomy Guide, Publication 811.
Nitrogen applications have still not been accomplished in some extremely wet areas. In these areas aerial application should definitely be considered immediately. If this option is not available, nitrogen applications should still be accomplished as soon as ground conditions permit. Reduce nitrogen applications by 11 kg/ha (10 pounds/acre) for every week beyond GS 30 that passes before N can be applied.

Spring Cereals
Frost seeded crops are showing rapid growth, and are beginning stem elongation (GS 30-31). Cereals planted early into dry soil are tillering (GS 21). Some seeding is still underway in Northern Ontario. Some acreage remains unplanted in wet areas of Grey and Bruce Counties and east of Toronto. These acres will likely be switched to an alternate crop. Cereal yields decline rapidly (1.5 bu/ac/day) when seeded after May 10th. If spring cereals are required for the straw and seeding is late, shift to 6-row barley varieties which tolerate heat stress and late planting better than other cereal types.

Weed control should become a priority in advanced crops. Target the 3 to 5 leaf stage (GS 13-21) for the best results and the highest yield impacts. A new on-line herbicide selection tool, http://www.weedpro75.com is available to help with cereal herbicide selection. This tool offers both the cleanest field herbicide option and the most economical herbicide choice for each cereal grain, including underseeded forage criteria.

Soybeans

Relatively few soybeans have been planted to date (5%) except in the extreme southwest on lighter soils or where conditions have been dryer.

Supplies of conventional soybean herbicides are in very short supply. Supply warehouses are sold out in many cases. Supplies of herbicides at retail dealers varies considerably. Growers may have to try several locations to get the herbicide of choice, or look at alternative herbicides in conventional soybeans.
A burndown herbicide treatment to eliminate emerged weeds is strongly recommended for no-till soybeans. Research by Dr. Francois Tardiff has shown that yields can be reduced by as much as 11% when burndowns are delayed until the cotyledon stage of the soybean crop. Glyphosate burndowns should be applied 5-7 days before planting to ensure adequate translocation into perennial weeds. If annual weeds are the target, a three day pre-plant interval is sufficient. When weather forces planting closer to application, the benefit of the burndown is still significant. Use the rainfast period of the product as a minimum time interval between application and planting, recognizing that weed control will be somewhat reduced.
A burndown treatment is especially critical in conventional (non glyphosate tolerant) beans, because post emergent options are limited. If a pre-plant burndown in no-till soybeans was not applied, be careful not to apply glyphosate too close to the emergence of conventional beans. Soybeans can emerge within 4 to 5 days of planting. In pre-emergent applications, apply glyphosate within three days of planting or before the beans start to crack the ground. If any soil cracking is evident, do not apply glyphosate! Wait until the conventional beans have emerged and use an early post-emergent spray.
Where burndowns are delayed due to wet soil conditions, increase herbicide rates and target appropriate herbicides to ensure adequate weed control. Large dandelions and perennial weeds require higher glyphosate rates. Large spreading atriplex can be difficult to control, with the addition of metribuzin offering improved efficacy. Check Publication 75, The Guide to Weed Control or www.ontarioweeds.com for product efficacy.

Spring Canola
Unseasonally cold conditions has delayed canola emergence with April planted stands emerging in about 2 weeks. Planting in southern Ontario is 80% complete, and Northern Ontario varies from 20 to 60% planted. Target a constant seeding depth of 1.25 – 2.5 cm (½ - 1 inch). It may be necessary to slow down to achieve a consistent depth. In southern Ontario, avoid planting canola into late May-June because of the high risk of swede midge injury.
Flea bettles will soon begin emerging from overwintering sites. At temperatures of 15 – 20ºC, flea beetles become much more active, taking flight in search of food. Populations can explode under warm, calm sunny weather. Seed treatments provide 2 to 4 weeks of control under light to moderate flea beetle pressure. Canola stands should be monitored for 3-4 weeks following emergence. For information on scouting and control, refer to OMAFRA Publication 811, Agronomy Guide and Publication 812, Field Crop Protection Guide.

Forage Report

Weed Control In New Seedings
Early planted new seedings should be scouted for annual broadleaf weeds. The risk of injury to alfalfa seedlings is greatly increased when 2,4-DB application is made outside of the first to the third trifoliate stage window. Note that page 102 in Publication 75, Guide To Weed Control has the incorrect product rate for 2,4-DB applied to underseeded cereals. The correct product rate is 0.7 to 0.9 L/ac when the formulation is 625 g/L. Field experience has demonstrated that reducing the rate of herbicide can reduce the risk of injury to alfalfa seedlings while providing acceptable suppression or control of weed seedlings.

Alfalfa Weevil
Alfalfa weevil larvae have been detected feeding on new alfalfa growth in the south-west, so scouting should begin. Damage usually shows up first on areas that warm the quickest, such as south-facing slopes. Alfalfa weevil feeding damage starts as pinholes in the leaves and progresses to feeding between the leaf veins, resulting in a skeletonized appearance. Alfalfa fields should be walked and properly scouted because “windshield” scouting will only detect a problem after damage has become severe. Larvae are bright green with a distinctive white stripe down the centre of the back. Insecticides are only recommended when cutting is impractical, such as when the alfalfa is in the pre-bud stage. Cutting before the bud stage can result in lower yields and extensive feeding damage to second-cut regrowth. Refer to OMAFRA Publications 812 Field Crop Protection Guide, and 811 Agronomy Guide.

Pasture
Management during the first round of rotational grazing can affect the productivity of the pasture for the rest of the summer. One of the common mistakes is not rotating quickly enough between paddocks. Livestock should be rotated quickly through the paddocks so that all plants have been bitten off before they have an opportunity to produce a seed head. Remember the phrase “the faster the grass is growing the faster the rotation”. The last paddock in the rotation should be grazed before the seed heads emerge. If the early flush of grass gets ahead of the livestock, it is best to bypass those paddocks completely, harvest an early cut of hay/haylage, and graze the second growth.




 

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