WEEKLY UPDATES

Crop Report June 25, 2009
Posted on June 25, 2009 at 15:43:48  
Ontario Field Crop Report
June 25, 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 window of opportunity to manage the wheat crop has closed. Fusarium is showing at low levels in advanced fields in the southwest. Look for partially bleached heads to identify this disease. We have escaped any major problem with this nemesis, although there may well be a few isolated “hot spots”.

Now is the time for BIN CLEANOUT! Preparing bins properly for wheat storage is a key component for avoiding disasters. See the June 26 issue of CropPest for details on proper cleanout and insect eradication (www.omafra.gov.on.ca/croppest/).

Spring Cereals
Spring cereals are heading which is the application window for fusarium control if it is required in spring wheat. USE THE RIGHT NOZZLES IF APPLYING FUNGICIDE TO SPRING WHEAT! There are only two nozzle configurations that work properly; alternating turbo floodjets or forward back nozzles operated 15º off horizontal. Twin jet or flat fan nozzles reduce efficacy by up to 50%. If you cannot use the right nozzles, why would you spray? Research trials in eastern Ontario have shown that Proline is significantly more effective than Folicur in spring wheat, so Proline is the product of choice. See www.weathercentral.ca for more information.

Aphid pressure continues at high levels in fields across the province. SCOUT! Populations of aphids in a few fields have exceeded threshold (15/stem prior to heading, 50/head once headed). Cereal leaf beetle continues to be found in Norfolk County above threshold levels. Control where warranted. See Publication 812, Field Crop Protection Guide.

Be sure to apply a fungicide at flag leaf stage in oat. Crown rust resistance has broken down and as a result crown rust will significantly impact yields in unsprayed fields. Loose smut has been reported in many heading barley crops. Look for heads with no seed, but masses of black spores that blow in the wind for this disease. Do not keep these fields for seed. Alternatively ensure excellent coverage of the seed with sufficient rates of fungicide, although this practice is less desirable than starting with “clean” seed. Otherwise most fields have reasonably low levels of disease.

Forages
Hay Storage
Remove bales from the field as quickly as possible before regrowth begins. Minimizing tractor and wagon traffic prevents alfalfa crown damage and subsequent yield loss. Refer to “Managing The Effect of Wheel Traffic On Forage Yields” on the OMAFRA Forage website www.omafra.gov.on.ca/english/crops/field/forages.html.

Hay storage is often a weak link to producing quality forage. To minimize spoilage losses, bales stored outside should be properly covered to shed rain and snow. Wicking of moisture can be very significant, so use pallets or crushed stone to keep bales off the ground. Six inches of spoilage around the outside of a round bale represents 20% of the volume of a 5 foot diameter bale, and 25% of the volume of a 4 foot bale. This is equivalent to leaving 10 acres of hay out of every 40 in the field to rot. The cost of indoor storage is only a small proportion of the total cost of producing hay, and is easily recoverable by maintaining forage quality and minimizing spoilage losses. Proper hay storage ventilation is important so that moisture can continue to dissipate from bales. The use of pallets prevents spoilage of the bottom row of bales. Hay intended for the horse market should not be allowed to sun bleach. Refer to www.omafra.gov.on.ca/english/engineer/facts/93-005.htm.

Potato Leafhoppers
Potato leafhoppers (PLH) have arrived in some areas, so begin scouting. Leafhopper damage in alfalfa is often mistaken for moisture or heat stress. New seedings are very susceptible and can be permanently damaged with yields being dramatically lowered. Decreased stand vigour results in slow regrowth and increased winterkill. Adult leafhoppers are 1/8th” (0.3cm) long, lime green and wedge-shaped. Leafhoppers feed by inserting a stylet into a leaf midrib and sucking plant juices. This action also injects a toxin into the alfalfa. The result is a wedge-shaped “hopperburn” on the leaf tips, reduced stem elongation and root development, and stunting. Refer to the OMAFRA Publications 811, Agronomy Guide and 812, Field Crop Protection Guide for scouting, threshold and insecticide information. Farmers in high risk areas, such as the Lake Erie area and the Niagara region, should consider PLH resistant alfalfa varieties.

Cereal Forage
Harvesting a cereal companion crop early as silage instead of grain is a good method to reduce weed competition and improve alfalfa establishment. Early harvest should allow for a second-cut of the underseeded forage before the end of summer. The stage of cereal maturity at cutting should match the livestock nutrition requirements. The optimum time to harvest for forage is when the cereal nurse crop is at the boot stage (higher nutritional quality) to early-heading stage (higher yield). Watch maturity closely as cereals advance through the various stages very quickly.


Pasture
Once grass heads emerge, nutritional quality decreases and growth slows. Pastures with lots of seed heads visible should be clipped to remove the seed heads and stimulate new plant growth. Weeds are also controlled by removing flowers and seed heads. Clipping should be done at a height of 4-8 inches (10-20 cm) to leave an abundance of leaf area for more rapid regrowth.

Edible Beans
Edible bean stands are adequate for the most part, with very few replants. Leafhoppers can be found in low numbers in most fields. Seed treatment with thiamethoxam (Cruiser) will provide control for 4-6 weeks following planting. Watch for numbers to build quickly as leafhoppers move in from alfalfa fields being harvested. Continue to scout before deciding to spray. Hot weather favours development and nymphs hatch in about 10 days. The action threshold at the unifoliate stage is 0.25 insects/plant, 0.5/trifoliate and 1/trifoliate at second and fourth trifoliate respectively. Mexican Bean beetle has been reported in a few areas. Scout fields especially along field borders looking for adult beetles and large holes in leaves. The adults resemble lady beetles, but differ by having 16 small black spots on their coppery-red back and head. Significant yield loss does not occur until up to 35% defoliation occurs prior to bloom stage. Bean Leaf beetle can also cause similar feeding damage.

Canola
Early spring canola is in full flower. Cabbage Seedpod weevil is present in flowering canola, although populations have been below threshold (2-4 per sweep). Scouting should focus on the adults, since only the adults can be controlled. Weevils will begin migrating into canola at bud stage and peak at early flowering. Adults are active on sunny warm days feeding on flower buds and laying eggs in pods. Scouting at this time will also allow detection of lygus and tarnished bug. Lygus bugs are readily abundant in fencerows this year. Lygus bug populations prefer hot, dry conditions. It is important not to spray prior to these insects reaching threshold, because of the impact on pollinating bees and other beneficials. For threshold information see Publication 812 Field Crop Protection Guide.

Stands of later planted canola look good, and are now in the 4 leaf to bolting stage. Scout late planted canola for swede midge and flea beetles. Canola is most susceptible to yield loss from swede midge prior to bolting. Flea beetle populations up to 4 leaf stage require monitoring. Refer to Agronomy Guide for further information.

If sulphur fertilizer was not applied prior to planting, check fields for visual signs of deficiency. Older leaves will appear mottled with intervienal yellowing. In severe deficiencies, leaves appear cupped with purpling of margins and undersides. Canola in the bolting to early flowering stage has the greatest demand for sulphur. Corrective application of soil applied sulphur can be made up to late bolting.

Soybeans
The majority of the Ontario soybean crop is in good to excellent condition. There has been tremendous plant growth over the last week because of the warm weather. Narrow rows planted early are well on the way to a closed canopy by the first of July. Most of the crop is in the V2-V4 (second-fourth trifoliate) growth stage. In those counties where dry areas remain, emergence has been slow but most stands are acceptable. Only a few replants have been necessary in the province.

Annual grasses are growing rapidly. Pre-emergent herbicides have worked well where moisture was sufficient but in dry areas weed escapes are evident. Graminicides need to be applied as soon as possible. If grasses get to the 6th leaf stage they become much harder to control. Where growers are controlling volunteer corn in soybeans, remember to add sufficient surfactant.

A few growers in southwestern Ontario attempt to grow soybeans immediately following the harvest of a winter cereal or a pea crop. Unfortunately, double cropping in Ontario is often unsuccessful. This practice will only succeed if sufficient moisture is available for quick emergence and September stays warm enough for the crop to finish. Even under good conditions the yield potential of a crop planted in early July is only 20-25 bu/ac. Do not take out a good read clover stand to double crop soybeans. The benefits of the clover will outweigh the risk involved with double cropping soybeans. If double cropping is attempted leave 20 cm (8 inches) of wheat stubble to promote elongation and higher pod set. Plant 1 cm (1/2 inches) into moisture but not deeper than 7.5 cm (3 inches). Plant in narrow rows with a high population (250 000 seeds/acre) to increase yield potential.

Soybean aphid numbers are increasing slowly but populations have been found across a wider geography than last week. Weather conditions and the level of beneficial insects will determine the rate of reproduction. Check the underside of newly emerged trifoliate leaves for small yellow-green aphids. Monitor aphids but do not control until populations reach threshold levels which is 250 aphids per plant and increasing on 80% of plants at the R1-R5 stage. There is no threshold during the V stages of soybean development and spraying is not recommended. Adding an insecticide to a herbicide application when the population is below threshold is not recommended as this will destroy beneficial insects and make the aphid problem worse later on. Current information on insects in field crops may be viewed on the web at http://bautebugblog.com or in Crop Pest Ontario.

Corn
Warmer conditions across the province resulted in significant corn growth this past week. For the 7 day period ending June 22, CHU accumulation was close to or slightly above the 30 year normal. However, many locations still remain approximately 10 % behind the 30 year normal CHU accumulation, when measured from May 1. Ottawa for example, registered 166 CHU from June 16 to June 22, 2009 (30 year normal is 162). Total CHU since May 1 is 802 CHU (30 year normal is 890). Corn moves through 2 leaf stages for every 150 CHU accumulated.

Although growth and colour has improved across nearly all corn fields, much of the corn planted under less than ideal soil conditions have both populations and uniformity which are less than ideal.

Weed control for the most part was finished off this week. Weeds that emerged with the crop or shortly after must be controlled as soon as possible. Weeds that emerge after the 8 leaf stage of the crop are usually an insignificant threat to yield.

Across most areas sidedressing nitrogen is in its final stages. Growers still trying to determine N rates for those final sidedressing operations should consider a Pre-Sidedress Nitrogen Test (PSNT) as some growers have reported high residual soil nitrates this spring allowing them to trim N rates accordingly. Taking a soil N test is the only way to verify if this is possible in any given field.



 

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