WEEKLY UPDATES

Crop Report June 18, 2009
Posted on June 19, 2009 at 11:29:15  
Ontario Field Crop Report
June 18th, 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 the new edition of Publication 811 Agronomy Guide for Field Crops ($30), 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.

Winter Cereals
The majority of the crop is at pollination to early milk stage. The crop is moving beyond the fusarium control window. Late application of fungicides (day 5 Folicur, day 8 Proline) will not provide acceptable fusarium control although leaf and other head diseases will be controlled if present. Consult the fungicide product label regarding restrictions on the pre-harvest interval.

Physiological fleck remains quite evident in many wheat fields. This disorder continues to be misdiagnosed as disease. Leaf and stripe rust levels are building in Essex County with the probability of spread to other regions likely. As temperatures rise, stripe rust development will slow while leaf rust will develop more rapidly. The early arrival of rust puts later wheat crops at more risk from the disease. Other controllable leaf diseases remain at low levels in most fields. Symptoms of viral diseases and cephalosporium stripe (for which there is no control) continue to develop in the crop as cool temperatures favour disease development. It is important to scout wheat fields as general trends of low disease can be quite different in specific fields.

Spring Cereals
Most of the spring wheat is at growth stages 37-47 (flag leaf to head in boot). Frost or early seeded spring cereals are now in head. It is too late to spray spring cereals for weed control. If weed pressure is heavy, plan to use a pre-harvest burndown.

Aphid pressure is significant in many fields across the province. SCOUT! A few fields have been found above threshold (15/stem prior to heading, 50/head once headed). Control where warranted. Refer to Publication 812, Field Crop Protection Guide, for recommendations on appropriate treatment options.

Leaf disease pressure remains very low. The main leaf diseases present are powdery mildew and septoria leaf spot on wheat, scald on barley, and some septoria leaf spot on oats. Headline EC, Stratego 250 EC and Quilt applications should be made by the flag leaf fully emerged stage (GS 39). Tilt 250E and Bumper 418 EC can be applied up to the head half emerged stage (G.S. 49-55). In most fields, growers will be able to delay fungicide decisions until Proline or Folicur timing for fusarium control.

Early fields are approaching the stage for fusarium control. For fusarium head blight control, Proline or Folicur should be applied from Day 2 to Day 4. Day 0 is when 75% of the wheat heads are fully emerged. You can monitor fusarium risk on the site-specific DONcast available at www.weathercentral.ca . It is extremely important to estimate a heading date and update this heading data as it gets close to a spray decision. Once heading is imminent, the observed weather will be factored into the model and the DON forecast will change frequently.

Proper sprayer tank and end cap cleanout is essential if fungicides are to be applied to wheat at fusarium timing. Use a proper tank cleaner and remove all end caps while flushing the boom. Wheat is very sensitive to herbicide injury at this stage.

Corn
The early planted corn has cleared the 8th leaf stage in some parts of the province; the majority of the crop is in the 6-7 leaf stage. Crop Heat Units in many areas remain behind the 30 year normal by about 10%. Typically in Southern Ontario at this date, corn should be around the 8th leaf stage, having accumulated 750 to 800 CHU since planting.

Frequent rains have benefited corn that was planted under less than ideal conditions, allowing reasonable development. However, in areas that have been dry over the last several weeks, plant populations are low and stands are particularly uneven. Now is an excellent time to assess plant population and uniformity of stand. Pay particular attention to the number of plants that may be 2 leaves or more behind neighbouring plants. These delayed plants impose competition to more advanced plants and are often an indication of problems associated with the planter or planting conditions. Diagnosing side-wall compaction, open seed slots or poor seed depth uniformity may help you assess changes that need to be made to your planter to improve planter performance in tough soil conditions.

Controlling weeds that have gone unchecked should be the number one priority as the corn plants move through the 5-8 leaf stage. In situations where a re-spray or a second application of glyphosate is being considered, remember that the threshold density of escaped grasses is much higher than for escaped broadleaf weeds. One green foxtail escape in 4 feet (1.2 m) of row (30 inch / 76 cm rows) reduces corn yield potential by only 2%, compared to a pigweed escape that can cause an 11% yield loss.

Forages
Forage harvest continues under variable weather conditions. Yield is lower than expected in many fields while quality varies with maturity and field condition. Recent harvest weather has been inconsistent resulting in some hay being stored at higher than ideal moisture. Monitoring hay for heating is critical ten to twenty days after harvest. Heating is most common in hay that was not sufficiently dry, but can also occur in haylage that was over-dry. Check the mow or silo with a long metal rod, or a pipe with a thermometer. If the rod feels hot, but you can still hold on to it the temperature is in the 65 C range. In this situation, monitor the temperature daily since the mow is approaching the danger zone. If the rod is too hot to hold in your hand immediately after it is removed from the hay, the temperature is about 80C. At this temperature the fire department should be called and hay should be removed from the mow immediately. This is a dangerous situation; do not work alone.

Immediately following first cut is an ideal time to apply fertilizer or liquid manure, since the material can be applied with minimal crop tramping and soil compaction. Apply manure as soon after harvest as possible, ideally to older stands and/or stands with a higher portion of grasses.

Pasture
Pastures are being clipped, or they should be. Most fields have developed a good base that will carry them well into summer. Supplemental feeding may be required in some fields located in dry areas of the province.

Soybeans
Warmer temperatures have improved emergence and growth of soybeans. Plant populations are adequate in most areas, although some replanting has occurred on heavier soil types. Advanced soybeans are V3- V4, but most are at the first to second trifoliate stage. Soil applied herbicide programs are performing well, with the exception of a few dry areas. Post emergent weed control is behind schedule, with weeds getting ahead of the crop in some cases. The yield losses due to weed interference are minimized if the soybean crop is kept weed-free from the 1st to 3rd trifoliate stage. Scout fields now for volunteer corn which is advancing quickly. Volunteer corn is much easier to control at early leaf stages.

Bean leaf beetle feeding has been observed in some fields in the southwestern counties. Scout fields in counties where the adult is known to over winter. This area extends up to southern Huron and Wellington counties. Signs of feeding are clipping of leaves or circular holes. Plants are most susceptible up to the V3 stage. Thiamethoxam (Cruiser) seed treatment provides effective control of early season adults. Populations have been below the action threshold of 16 adult beetles per foot of row in early seedling stages.

Soybean aphids have been found at very low levels in fields from Lambton County to Ottawa. Most fields have only 5-10% of the plants infested with a few aphids per plant, though some states are starting to find fields with 30-40 aphids per plant. This is the first time Ontario has experienced such widespread colonization of young V stage soybeans. No thresholds have been developed for these early season infestations and it is questionable as to whether there would be a yield response to spraying. There is a greater risk of killing natural enemies that are migrating to the soybean fields which in turn could cause the aphid populations to increase. Weather conditions in June have been ideal for aphid development. Scout any emerged soybean fields, paying particular attention to those fields not treated with thiamethoxam (Cruiser seed treatment). Check the underside of newly emerged trifoliate leaves for small yellow-green aphids. The presence of ants on soybeans is a good sign that aphids may be present. Current information on insects in field crops may be viewed on the web at www.bautebugblog.com or in CropPest Ontario

Nitrogen fertilizers are not generally required for soybeans. Nodulation of soybeans may be observed 3-5 weeks after planting. In virgin fields, nodules will be located on the taproot. In fields that have previously had soybeans in them, nodules will also be found on lateral roots. Five to ten nodules per plant are adequate at this stage. If there is a nodulation failure and soybeans are pale green and N-deficient, consider applying 50 kg/ha of N at first flower. Apply urea or calcium ammonium nitrate when the foliage is dry.

Edible Beans
Planting is 90% complete as of June 17. Emergence of early planted edible beans has been uneven and often requiring 21+ days. Emergence of later planted beans has been more rapid and populations are generally good, except on a few clay soils where crusting occurred.

For an adequate stand of edible beans, there should be a minimum 66 to 75% of a full stand since edible beans have a limited ability to branch and compensate for thin stands. The minimum number of healthy plants should be 2 – 3/ft (6-10/m) in 15” – 21” (38-53 cm) rows and 3 - 4 (10-13/m) in 30” (76 cm) rows. These minimum stand counts assume good growing conditions, remaining plants are healthy, the stand is uniform, and the field has good soil conditions (not compacted).

Thiamethoxam (Cruiser) seed treatment provides control of leafhoppers for 3-6 weeks following planting. Bean leaf beetles that are now actively feeding in some soybean fields in southwestern counties, may move on to edible beans. Cruiser seed treatment controls early populations of bean leaf beetles.

Scout fields for weed escapes from soil applied herbicides. Dry conditions following application of pre-emergent herbicides can allow weeds to emerge before rainfall can activate the herbicide. Wait until beans have at least one trifoliate before applying post emergent broadleaf herbicides (i.e. Basagran, Reflex). These products act primarily by contact, therefore, it is essential to achieve good coverage by following recommended water volumes. Watch for differences in tolerance of different bean types to post emergent herbicides.

Canola
Canola is advancing quickly, with early plantings now bolting. Weed control is a high priority. Since canola is slow to develop up to 4 leaf stage it is not competitive with weeds during the first month of growth. Early season competition from weeds significantly reduces yields when left uncontrolled. Yield losses from late herbicide applications are irreversible. The optimum weed control period is the 2-4 leaf stage.

Insecticide seed treatments provide control of flea beetles during first month following planting. High populations may not be adequately controlled. Populations are generally low, but can increase rapidly with warm sunny weather, requiring constant monitoring.

 

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