Ontario Field Crop Report
June 12, 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.

Corn
Warmer temperatures have resulted in rapid corn development over the last week.  CHU accumulation for the first nine days of June were 224, 212 and 209 for London, Waterloo and Ottawa respectively; roughly two-thirds of the total for all of May.  Corn stands are, for the most part, quite uniform and emergence issues have been limited.

Early planted corn is close to or beyond the 6-leaf stage and, if post-emergent herbicides are still to be applied, be sure to check the labels to see that the product fits the crop stage.

Fields where an early post-emergent application of a non-residual herbicide has been applied should be monitored for subsequent flushes of weeds.  Warm, wet conditions may have speeded the germination of weeds and another application may be required to keep the crop clean through the critical period.

Sidedressing nitrogen has been delayed in some areas due to wet conditions. Ontario’s recommendations for N rates on corn can be found at www.gocorn.net and clicking on the Nitrogen Calculator.  The pre-sidedress nitrogen soil test (PSNT), can also assist in fine-tuning sidedress N recommendations.  Soil samples need to be taken pre-sidedress to a depth of 30 cm (12").  Refer to pages 65-66, OMAFRA Publication 811, Agronomy Guide.

Forage Report
Harvest conditions have been challenging this spring, as many areas have received frequent showers.  Depending on the amount of weathering, the feed value of the forage may not have been seriously impaired, but harvest management may have to be adjusted.

The loss of soluble carbohydrates when forage is rained on can make the forage more difficult to ensile.  This loss is much greater for hay that is almost dry compared to hay that is fresh cut.  Wilted hay that has been rained on may still be suitable for chopped haylage, but may not keep as well as round bale silage due to slow fermentation.  Hay that has been rained on needs to be dryer before storage than hay that has not been rained on, because soil splashed up from the ground has inoculated the hay with a heavy load of spoilage organisms.

Whether the forage has been weathered or not, be sure to collect samples as the forage is harvested for analysis.  Representative samples can be accumulated as the haylage is going into the silo or the bag, placed in plastic bags, and frozen until they are sent to the lab.  These samples not only form the basis for ration balancing this winter, but they can act as tissue samples to pinpoint any problems with your fertilizer program.

Hay/haylage heating can lead to spontaneous combustion.  Spontaneous heating and combustion occurs when sufficient moisture, oxygen and organic matter are present together to support the growth of bacteria and moulds.  Ensure that hay is dry enough to be baled and stored.  Spontaneous combustion for hay usually occurs within the first two months of storage.  Check for heating by using a metal rod or pipe that can be inserted 6-8 feet into the hay.  For further information, refer to the OMAFRA Factsheet ‘Silo and Hay Mow Fires on Your Farm’.

Canola

Most stands of spring canola are uniform and rapidly advancing.  The window has closed for weed control applications in early fields, and is rapidly ending in later fields.  Flea beetle pressure has been low in many fields and control is not warranted past the 4-leaf stage.  Canola that is at the 5-6 leaf stage will soon begin to bolt and flowering will typically begin within 10-14 days.  Monitor fields in flower for cabbage seedpod weevil.  Insecticide is necessary at thresholds of two weevils per sweep.  Spray application should be done at the 10-20% bloom stage (2-4 days after flowering starts) to control the weevils before they lay their eggs on the pods.  Apply insecticides after 7:00 p.m. when bees are not foraging, or if this is not possible, before 7:00 a.m.

If a fungicide is to be applied for white mould (sclerotinia) protection, initial application needs to be made at 20-50% bloom stage.  Twenty percent flower occurs when there are 14-20 open flowers on the main stem, about 5-6 days after flowering begins.  Fungicides act as a protectant and must be applied prior to infection.  The goal of fungicide application is to cover as many flower petals as possible before they drop off.  Factors that increase the risk of white mould include dense crop canopy, showers in the forecast with moderate temperatures (below 25°C) during flowering, and saturated soil in the two weeks leading up to flowering.

Soybean Report
Soybean planting wrapped up the first week of June. Emergence has been good in most fields, with some crusting concerns from heavy rains in a few areas.  If you are considering re-planting and there are 100,000 plants/acre, leave the stand.  (100,000 plants/acre= 16 plants in a 36” hula hoop, 14 in a 33”, and 11 in a 30”).  The exception to this rule may be very heavy clay soils.  Do not change maturity on soybean varieties if re-planting now.  Stay with full season beans.  See the Agronomy Guide (OMAFRA Publication 811) for more details.

Weed control will be the biggest priority as yield losses due to weed interference are minimized if the soybean crop is kept weed-free from the first to third trifoliate stage.

Some bean leaf beetle feeding has been observed but generally at levels below the action threshold which ranges from 16 adult beetles per foot of row in early seedling stages to over 39 per foot of row at V2+ stages.  If leaf defoliation exceeds the thresholds levels shown in Table 4-20 of the Agronomy Guide (OMAFRA Publication 811), then treatment may be warranted.

Cereals
Winter Cereals: The majority of the crop is fully headed to the end of the pollination stage.  Early planted fields are now beyond where fusarium control products can be applied.  On later fields, application of fusarium products must occur now.  Late application of fungicides for fusarium (day 6 and beyond), will not provide acceptable fusarium control, but will reduce other leaf and head diseases.  Consult the product label for pre-harvest interval.

Continued wet weather has been favourable for powdery mildew development in some fields.  Rust pustules are developing in low levels in some wheat fields, with the exception of the variety Vienna, where high levels have been reported.  Research has shown that fusarium control products are also effective for both of these diseases.

Armyworms can be found in many wheat fields.  Scout all cereal crops in the evening or early morning when armyworms are actively feeding.  Control is warranted if there are four unparasitized larvae, smaller than 2.5 cm (1") per square foot.  If the larvae are almost full grown (about 4 cm or 1½" long), there is no benefit in applying insecticide since most of the feeding damage has already been done.  Look for natural parasitism of armyworms by a parasitic fly that lays its eggs on the backs of armyworms.  If there are other grass type crops such as corn or grass hay fields nearby, the armyworms will ‘march’ over to the next crop.  Spraying the border of these fields may be sufficient to stop the armyworms.  Note that the pre-harvest interval for most control products is 14-28 days depending on the product and the crop to be treated.  For further information, see OMAFRA Publication 812, Field Crop Protection Guide, for recommended insecticides.

Spring Cereals: Early planted spring cereals are at Growth Stage 32-37 (second node to flag leaf emergence) and well beyond the stage for herbicide applications in most fields.  Disease levels remain low in most fields.  Continue scouting cereals for the presence of leaf diseases, watching the oat crop, in particular, for signs of rust infection.  As cereals reach the flag leaf stage, growers must decide if a foliar fungicide is required.

Cereal aphids are noticeable in many spring cereal fields, but still below economical thresholds.  The control threshold is 12-15 aphids per stem pre-heading, and 50 aphids per head once headed.  Scout!  Examine 20 stems in five areas across the field.  Shake the plants over a piece of paper and count the number of aphids present.  Make note of any predators present and whether the aphids are parasitized or infected with a fungus.  Spray immediately when the threshold has been reached.  For further information, see OMAFRA Publication 812, Field Crop Protection Guide, for recommended insecticides.

 

Edible Beans
Wet weather has delayed planting in most areas, with 10-30% of the crop planted provincially.  Emergence has generally been good.  Crusting issues have been a concern on heavy soil types.  If planting continues to be delayed, consider when beans will mature before continuing to plant.  When late planting cannot be avoided, consider switching to soybeans.