Ontario Field Crop Report
April 30, 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.

Winter Cereals
Winter survival for winter wheat was generally excellent despite an extended winter.  Winter barley suffered significantly, indicating that the winter was indeed harder than the last seven years.  Wheat on heavy clay soils in Lambton/Kent/Elgin was hardest hit, with frequent melts, rain and immediate freezing in this area all winter.  As much as 20% of the wheat in this localized area may be destroyed.  Early planted wheat survived much better than late planted wheat.  Ultra early planted wheat suffered damage in the traditional snow belt areas from snow mould (Michrodochium nivale), particularly along woodlots and fence rows.  However, survival was excellent in general with only 2% of the crop reported to have winterkill issues province wide.  Record acreage appears on track for excellent yield potential!

Nitrogen applications were completed in a timely fashion in mid-late April with excellent soil conditions as spring arrived with dry weather.  Many growers have expressed concern over nitrogen volatilization loss as dry weather persisted with no rain to move the nitrogen into the soil.  However, these concerns are “theoretical”, and past experience would indicate that losses will be negligible.  There is no science to support the need for additional nitrogen at this time.

Weed control got underway during the week of April 21st, and growers that jumped at this chance sprayed wheat under virtually ideal conditions; warm nights and rapidly growing weeds.  Unfortunately, most growers did not jump at this early opportunity with less than 10% of the wheat crop sprayed under these excellent conditions.  With temperatures below 0ºC overnight this week (April 28th), growers are forced to wait for warmer temperatures to spray.  The wheat crop has moved rapidly forward with early fields reaching Zadok’s 31 (first node) by April 26th, meaning that weed control should have been applied by this time.  The message of the benefits of early weed control in wheat seems to hit resistance at both the farmer and agribusiness level.

Disease pressure in wheat remains at extremely low levels.  Septoria and mildew are beginning at very low levels in lush fields but are well below threshold.  Many growers will apply an early fungicide this year as high wheat prices support this increased management.  Growers should leave a check strip to determine how much yield benefit this early fungicide offers.

Grub damage is noticeable in some fields where Cruiser seed treatment was not used.   There are no effective rescue treatments available.  It is important to identify problem fields now and determine which grub is present.  Fields with a history of grub injury should be planted with insecticide seed treatments in the future and where possible have some form of tillage done.

Spring Cereals
Seeding is 75% complete with much of the crop planted into excellent soil conditions in late April.  Isolated pockets have remained too wet for planting.  Earliest plantings are up (Zadok’s 12 or 2 leaves) and look good.  There was little chance for frost seeding this year as once the snow melted, summer arrived.  Given current price levels, wheat acreage is up slightly while barley and oat acreage have dropped dramatically this year.  Growers should be on deck to spray spring cereals as optimum timing is at the third leaf stage for most herbicides.

Corn
A significant acreage of corn has been planted in the London area (up to 80%) and the first corn planted started to emerge over the weekend of April 26-27.  Much of the rest of the province has only 0-20% of the corn acreage planted. Soil temperatures at 10 cm (soil depth) were over 15ºC across many areas through the week of April 22nd and the soil was in good shape for planting.

With the cooler temperatures occurring the week of April 28th, be cautious of the temperature restrictions on early post corn herbicides if the crop has emerged, especially with the hormonal and sulfonylurea materials.

A significant area around Lake Simcoe is experiencing very high European chafer infestations. Fields of sandy to loamy soil should be checked for presence of the grubs.  If they are found in significant numbers, the use of seed applied insecticide is critical.  In some cases, heavy populations of this insect may require higher rates of insecticide (i.e Poncho 1250) or the application of granular insecticide applied in-furrow.

Fertilizer nitrogen rates should also be targeted to the realistic potential of the field to deliver yield.  Refer to the Ontario Nitrogen Calculator (www.gocorn.net) to estimate the amount of nitrogen required based on your best projections of corn price, crop yield and nitrogen costs.

If fields have dried significantly in your area be sure your planting operation promotes uniform placement of the seed in moist soil.  Be cautious, especially on light textured soils that fertilizer openers are operating at the correct distance from the row (generally 5 cm).  Dry fertilizer rates where urea is the N source should not exceed 75 kg/ha (67 lbs/ha), nitrogen and potash combined, in a 5 cm by 5 cm band.

Soybeans
Soybean seed harvested last fall at low moisture content is fragile and must be handled with care.  When handling seed lots augers or conveyors should be running slow and at full capacity to reduce seed damage.  Soybean seed treatments will not improve germination that was caused by a dry harvest last fall.

Ideally, soybeans should be planted when soil temperatures are above 10°C (50°F). Soybean seed that absorbs very cold water during the initial period after planting is at greater risk of reduced germination and vigour.  Soil temperatures during the first 8 –20 hours after planting are more critical to germination and vigour than subsequent soil temperatures.  Field experience has shown that a cold rain immediately after planting can reduce vigour.

Check your soybean seedlots (i.e. seeds/lb) and plant the correct number of seeds per acre, not pounds per acre.  Suggested seeding rates are:

                 194,000 seeds/acre for 7.5 inch (18cm) row spacing,
                 177,000 for 15 inch (36cm) row spacing,
                 172,000 for 22 inch (53cm) row spacing and
                 162,000 for 30 inch (71cm) row spacing.

Scout for weeds as a number of winter annual, biennial and perennial weeds have already emerged.  Select the pre-plant rate of glyphosate based on the most difficult weed species to control in the field.  For example, dandelion in some instances is already larger than 15 cm (6”) in diameter and will require a higher rate of glyphosate (i.e. 2L/ac) for control. Skipping a pre-plant burndown often results in yield losses from early season competition and reduced weed control since weeds are typically larger and harder to control. Applying glyphosate after planting and before crop emergence greatly reduces the control of many perennial weeds, particularly dandelion.

Overwintering bean leaf beetle adults will be active soon.  Fields first to emerge in their area will be most attractive to the overwintering adults.  Early planted fields in regions known to have a history of seedling injury due to bean leaf beetle should be planted with Cruiser treated seed.

Forages
Two warm weeks have brought life back to forage and pasture fields with most showing uniform growth of alfalfa and grasses.  In some areas of the province forage growth is up to a week ahead of normal.  Reports of winterkill, especially in eastern Ontario, are lower than other years, however, across the province some winterkill is evident on heavier soils and/or areas where soils suffered prolonged saturation or ice.  Bare spots in some fields, especially north of the GTA, could also be the result of European chafer and/or June Beetle grub feeding.  White grubs overwinter in the fields below the frost line.  In early spring they move to the soil surface and feed on plant roots, resulting in poor emergence and stunted plants. It is important to identify problem fields now and determine which type of grub is present.  No control options are available for the forage crop at this time.  If the grubs are chafers, which are annual grubs, the feeding will stop within the next few weeks so that the insect can pupate and become an adult.  If the damage is caused by June Beetle grubs, they live for three years in the soil and could feed throughout the summer.  Knowing which grub is causing the problem will help determine future plantings and control strategies.  Grubs are easy to find by moving the soil in the top few inches near bare spots or near wilting plants.  For additional information on identification and options, refer to http://www.omafra.gov.on.ca/english/crops/field/news/croptalk/2007/ct-1107a4.htm

Regardless of winter survival, spring is an excellent time to walk forage fields and assess the alfalfa stand for survival and plant health.  Choose several random areas in the field and count the number of healthy crown (plants) remaining.  The minimum number of healthy plants per square foot should be 12 to 20 plants for 1st year stand, 8 to 12 plants for second year stands and 5 plants for a third year or older stand.

When plants have about 15 cm (6 inches) of height, stems per crown can also help in assessing an alfalfa stand.  Consider replacing the stand if there are less than 40 stems per square foot, especially if the crown and root health is poor.  Older alfalfa stands which have been thinned-out can be reseeded with a drill as soon as the ground firms up using either red clover (3.5–5.5 kg/ha), white clover (2-4 kg/ha), orchard grass (3.5-5.5 kg/ha), or perennial ryegrass (4-5.5 kg/ha), depending on the anticipated future life of the stand.  Applying new alfalfa seed to an established alfalfa field, in order to thicken a stand, is rarely successful due to autotoxicity.

Planting of new forage stands is well underway, with the earliest planted fields emerged at the unifoliate stage. 

Perennial and winter-annual weeds, especially dandelions and shepherd’s purse are showing up and starting to bloom, especially in older stands.