Ontario Field Crop Report
May 21, 2008
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.
Insect Issues
With the continued delayed emergence of spring seeded crops due to cool wet weather, injury from soil borne insects is being reported. Insects such as millipedes, wireworms and seed corn maggots are the main concern, especially in higher organic matter soils or high crop residue conditions. Where Poncho 250 has been used, control should be adequate on all major species except millipedes. Slugs may also be a problem under these conditions. However, emergence delays could be associated with high populations of insects even if insecticide has been used. Monitor fields to determine the cause of emergence delays.
Winter Wheat
Advanced wheat fields are at Zadok’s 45 (boot visibly swollen), while the bulk of the crop is at Zadok’s 37-39 (flag leaf).
While cool temperatures have kept disease pressure low, it remains important to scout fields regularly since disease pressure can change rapidly. Focus on the top two leaves of the plant which are responsible for 90% of the yield. Fungicides containing strobulurin chemistry such as Headline, Stratego and Quilt can be applied up to the Zadok’s 39 (flag leaf fully emerged) stage. Do not apply strobulurins at Zadok’s 47 (boot stage) and beyond due to risk of increased DON levels. Fungicides containing triazole products such as Tilt and Bumper can be applied up to Zadok’s 55 (head ½ emerged) stage. This emphasizes the need to monitor the crop’s growth stage. Fungicide information is available in the Field Crop Protection Guide, OMAFRA Publication 812. http://www.omafra.gov.on.ca/english/crops/pub812/p812toc.html
The Fusarium Risk calculator (DONCast) for wheat is available at the Weather Innovations Incorporated (WIN) website at http://www.weatherinnovations.com/index.cfm
The field specific component of DONCast is free to growers this year. Knowing your heading date is key to predicting disease development. To predict DON levels in wheat, DONcast establishes the heading date (Day zero) at Zadok’s 59, when 75% of the wheat heads have fully emerged above the flag leaf. For DON control, timing of fungicide application is critical, with the target application date being Day 2. The optimum fungicide application window is from Days 1-4.
Spring Cereals
Early spring cereals are at Zadok’s 24 (most tillers formed), while much of the crop is at Zadok’s 21 (early tillering).
Broadleaf weeds should be sprayed between the three to five leaf stage (Zadok’s 13 to 26) of the crop. Weeds are advanced compared to the crop so herbicides should be applied in the first part of the crop spray window. Established dandelions are best controlled with dichloroprop/2,4-D (but do not use on oats). Annual grasses are also emerging and can be controlled with Achieve or Puma. DO NOT apply herbicides to spring cereals when temperatures are expected to drop below 3oC within 36 hours of application. Tankmixes of grass and broadleaf herbicides are of particular concern with adverse weather at or following application. If cool, cloudy conditions are forecasted, apply as two separate sprays four days apart (follow label recommendations). Refer to Guide to Weed Control, OMAFRA Publication 75, and product label for weeds controlled and application timing instructions http://www.omafra.gov.on.ca/english/crops/pub75/pub75toc.htm.
Leaf disease pressure remains low. Fields should be scouted for early signs of disease and control measures applied accordingly. In particular, watch oat fields for signs of rust infection.
Soybeans
Frequent showers have delayed soybean planting and, as of last week (May 21), less than 10% of the expected acreage had been planted. Better planting opportunities in eastern Ontario have seen 60% of the crop planted. Cool, wet soils in May have resulted in slow soybean emergence. At average soil temperatures of 10-13oC (50-55oF) soybeans can take 21 or more days to emerge while at 15-20oC (60-68oF) only 12-14 days are required. Soybeans have the ability to adjust to delays in planting. A one month delay in planting will generally delay maturity by only nine days. Therefore, do not consider switching to shorter day varieties until after mid June.
Successful soybean production starts with planting into soil that is sufficiently dry and warm (10oC). Planting into wet soils often results in seed slot smearing which may cause reduced lateral root growth and slower nodulation. The seed slot may also open up as the ground dries resulting in poor seed to soil contact. Ensure that soybeans are planted about 1.25 cm (½”) into moisture but not deeper than 6.25 cm (2 ½”) in total. Although this spring has been wet so far, it is not advised to plant soybeans too shallow. The top inch of soil may dry out quickly before the beans have a chance to establish.
Cool conditions have slowed the activity of pre-plant glyphosate burndown treatments. To help improve activity of burndown treatments, apply in the morning so that uptake occurs through the warmest part of the day, and increase the glyphosate rate slightly, particularly when used in combination with metribuzin. If perennial weeds are getting large (12.5 cm/5" or taller), then increasing the rate of glyphosate to 1.5 to 2.0 L/acre should be considered. When targeting the control of perennial weeds, wait 5-7 days after glyphosate application before planting. This will ensure adequate herbicide translocation occurs.
Corn
Corn planted April 17-25 is generally in the one to two leaf stage, while corn planted April 26-May 8 is in the spike to one leaf stage. Some intended corn acreage still exists, particularly in the central parts of the province and on heavy textured soils. Most growers still planning on planting corn should consider switching hybrids. For the week following May 25, consider planting hybrids that are rated for 100 CHU’s lower than your farm.
Crop Heat Unit (CHU) accumulation in the first 19 days of May has been 189, 170 and 215 for London, Waterloo and Ottawa respectively and corn emergence and growth has been slow.
Although corn requires temperatures above 10oC to grow, many weed species can emerge and grow at considerably cooler temperatures. If pre-emerge herbicide applications have been delayed because of poor weather or other field operations, be sure to examine the fit between your intended herbicide and the weeds present in the field regardless of corn size. For example, some pre-emerge herbicides may “reach back” and control grasses at the two leaf stage while others will not. Some changes in your weed control strategy may be warranted. Refer to Ontario’s Guide to Weed Control OMAFRA Publication 75 and product labels for information. Application of hormonal based herbicides under the cool conditions being experienced the week of May 19th can be injurious to corn. Delaying application until warmer weather is forecast is recommended for most herbicides based on the early staging of the corn crop in general.
Spring Canola
Although 85% of the crop is planted, continued showers and cold temperatures have delayed the completion of planting. Canola planted three to four weeks ago is now emerging. Although temperatures are cool, feeding from flea beetles is evident in emerged fields. Seed treatments provide protection from flea beetles for three to four weeks following planting. Flea beetle populations can build very rapidly under warm, sunny weather and exceed the action threshold of 25% damage in a matter of days. Scout fields to determine if a foliar insecticide application is required because of slow crop growth and/or high flea beetle populations. Check fields until plants are past the four true leaf stage (do not count the cotyledons) stage. Be sure to go back and check fields that have been sprayed for new flushes of flea beetles.
Edible Beans
Success in edible beans starts with seeding into a warm (>15°C), moist seedbed (1.25 cm/1/2 inch into moisture) which promotes rapid emergence and reduces the risk of injury from soil insects and early season root rot. Planting into cool, damp conditions is the greatest cause of poor stands. Manually check population and seeding depth during planting of every field. Planting deeper than 6.5 cm (2.5”) increases the impact of any crusting.
Edible bean seed moisture seems lower than normal which increases risk of mechanical damage. Be cautious using air seeders to ensure the air manifold is lined and watch air flow rates to minimize seed impact injury. It is a good practice to keep a sample of each seed lot planted, noting planting date(s) and field.
No-till seeding requires some in-row tillage (e.g. tillage coulters) to aid establishment and early root growth. To minimize planter bounce, use a constant field speed of 6.5-8kph (4-5mph).
The target seeding rate for white and black beans is 5-6 seeds per foot of row in 76 cm (30 inch) rows, or 3.5-4.5 seeds/foot in 38-53 cm (15-21 inch) rows. Seeding in narrower row widths is no longer recommended. The seeding rate for large size coloured beans is typically 3.5-5 seeds/foot in 76 cm (30 inch) rows, and 3-3.5 seeds/foot in 38-53 cm (15-21 inch) rows. Adding talc to the seed can improve seed flow. Increase seeding rates by 10% where conditions such as heavy soils and late planting pose a risk to germination and emergence. Edible beans have a low tolerance to environmental stress conditions.
The most typical nitrogen rate for edible beans is 45-67 kg/ha (40-60 lbs/ac).
Forages
Continued cool temperatures are slowing forage growth, with most fields showing 30 cm to 50 cm of growth. The earliest fields are seeing the alfalfa coming into bud and early grasses near heading.
Based on calendar dates, harvest may begin by the weekend of May 24-25. Since fields are just coming into bud, quality and yield may be compromised for this cut because of this early maturity harvest. Alfalfa requires a minimum of five weeks re-growth between cuts, so if you are targeting four cuts to meet normal quality and yield expectations, the first cut must be a minimum of 15 weeks earlier then the beginning of the critical fall harvest period. If the last cut needs to be taken by September 12, then the first cutting must occur before the end of May. If you are on a three cut system, then manage the cutting schedule to target the mid to full bud stage in order to maximize yield and quality. With many reports of alfalfa weevil feeding, scouting should continue, especially to new growth in early harvested fields.
Early season hay can be a challenge to get dried to safe moisture levels, particularly for storage in large square or hard core round bales. These larger packages do not “breathe” easily resulting in spoilage within the bales. Buffered propionic acid preservatives applied at baling can prevent mould growth. More information can be found at http://www.omafra.gov.on.ca/english/crops/facts/preventing.htm
Pasture
Proper management of pastures during this time is critical to obtain optimum forage quantity and quality throughout the remainder of the grazing season. It is critical to keep grasses growing vegetatively. Once plants head out, the vegetative leaf growth slows dramatically and the plants energy is directed to seed production.
Move livestock through the paddocks quickly so that most plants get at least part of the foliage bitten off. Pastures grazed too short at this time will experience slow re-growth and pasture production will be reduced for the remainder of the season. It is recommended to clip pastures where grasses have headed to stimulate new leaf growth. Clipping must be done early enough to allow the grasses to regrow before the “summer slump”. If a number of pastures are getting ahead of the cattle, consider making hay from one or two paddocks.