Ontario Field Crop Report
August 13, 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
The corn crop continues to be in excellent shape across much of Ontario. Continued wet conditions in parts of eastern Ontario, and on heavier soils in southern Ontario. are having some impact. Precipitation records are being broken throughout Ontario. For July, rain recorded (versus long term normals) for Waterloo, Hamilton, Peterborough and Trenton were 204 (92), 149 (87), 148 (67) and 102 (56) mm respectively.
The continued wet weather and lack of sunshine has not had big impacts on crop heat unit (CHU) accumulation. As of August 8, the CHU accumulations were 2316, 2038, 1888, 1862 and 2100 for Windsor, London, Waterloo, Peterborough and Ottawa respectively. The 2007 CHU averages up to this date for these sites, were 2420, 2045, 1793, 1743 and 1978 respectively. There is a 1,825 CHU requirement for corn to reach the blister stage (R2) and 2,000 CHU for the milk stage (R3). This would suggest that fields, in general, are no more than a week behind normal for crop development. If current weather trends hold, black layer maturity would be expected the end of the third week of September.
The moderate temperatures and ample rainfall have been excellent for pollination throughout Ontario. Even in fields with uneven crop, the extended pollen shed period has ensured excellent kernel set.
Scout for crop diseases such as fusarium. This will give ample time to address any issues that develop. Significant numbers of western bean cutworm moths have been found in traps in the Blyth area. Corn fields in this area should be scouted for egg masses and small larvae. For more information, refer to CropPest, August 8, 2008, which can be found at: http://www.omafra.gov.on.ca/english/crops/field/news/croppest/2008/12cpo08a4.htm
Hail damage has occurred in localized areas over the past several weeks. There are no management options to address hail damage at this point in the season. Crop yield losses predicted from hail damage vary greatly. Harvest is the true determiner of the impact of hail.
Soybeans
The majority of the soybean crop is between the R3 (beginning pod set) and R6 stage (full seed). Any stresses that occur prior to the R6 stage can result in significant yield losses.
Weather conditions have started to favour the increase in soybean aphids. Minnesota, and other regions in the US mid-west, is starting to see threshold levels of aphids. These aphids can get carried in on the frequently occurring weather fronts. Scouting is critical these next few weeks. Some sites in Ontario are starting to see aphid population increases. Consider a foliar insecticide when aphid populations continue to rise above 250 per plant during the R1 (beginning bloom), to R5 (beginning seed) stages. For more information on scouting and control of soybean aphids, refer to OMAFRA Publication 812, Field Crop Protection Guide.
First generation Bean Leaf Beetle (BLB) adults are now active. Defoliation by BLB is often over-estimated, especially since the feeding is typically concentrated at the top of the canopy where it is most obvious to a scout. Determine the percent defoliation by taking leaflets from the middle of the canopy, not just from the top of the plant. During the R1 (beginning bloom) to R4 (full pod) stages, it takes 15% defoliation before spray is necessary, especially in a year when the plants are not stressed from drought, and continuing to put out new leaves to compensate for the feeding damage.
Forage
Due to frequent showers and storms, harvesting quality hay continues to be extremely difficult across much of the province. Although forage growth has been excellent, there are not many hay fields that have been harvested without any rain-damage this summer. Growers who harvested at the time of optimum quality, were not able to get hay into storage without rain damage. Growers who waited for better weather, suffered significant losses of protein and energy due to delayed harvest, compounded by weathering as it rained again. “Horse quality” hay without any rain damage or mould is extremely short in supply! With the wetter and cooler summer and delayed harvest dates, forage analysis is essential for accurate ration formulation. Rain damaged hay has suffered both reduced quality and yield through the cumulative effects of leaf loss, leaching, respiration and mould.
The critical fall harvest period for alfalfa is a six week rest period preceding the average date of killing frost. Not harvesting during this period allows alfalfa plants to re-grow, build up sufficient root reserves, and reduce the risk of winterkill. Yield sacrificed by not harvesting during the critical harvest period is usually regained in first-cut yield the following spring. The critical fall harvest period begins as early as August 10 in northern Ontario, August 25-30 for eastern and central Ontario, and early-September in the southwest. Avoiding harvest during the critical fall harvest period is especially important on farms with a history of winterkill or with aggressive cutting schedules. For information on winterkill risk factors, including a map showing the dates for Critical Fall Harvest Period, refer to www.omafra.gov.on.ca/english/crops/pub811/5other.htm.
A high yielding alfalfa field can remove over 300 lbs/acre of potash from the soil. Potash deficiency shows up in alfalfa plants as small, white dots near the outside edge of the leaflets. If potassium levels in forage fields are low, fertilizing prior to the fall rest period with commercial potash or manure, will help to improve winter persistence as well as yield.
Pasture
Pastures continue to be very productive. Timely rains, coupled with rotational grazing, have allowed for good growth throughout July and into August. Where there are plans for stockpiling forage for late fall or early winter grazing, now is the time to stop grazing these fields. If there is considerable mature growth, clip them and apply 50-to80 pounds of nitrogen to grass pastures to promote growth. These stockpiled pastures will provide good quality, economical forage well after the end of the growing season.
As cereal harvest nears completion, cover crops can provide an excellent opportunity for late season grazing while reducing potential soil or wind erosion. A list of potential cover crops, their seeding rate and ideal fall planting date can be found at www.omafra.gov.on.ca/english/crops/pub811/2cover.htm.
Winter Cereals
Winter wheat harvest is about 85% complete in southwestern Ontario and about 40% complete in the rest of Ontario. Harvest is delayed due to the frequent rain showers. Yields have been average to above average. With harvest delays, quality held up much better than expected. But as inclement weather continues, quality is now deteriorating significantly in some areas. Mildew, sprouts and fusarium are the main reasons for downgrading.
Growers thinking about planting can look for the 2008 Winter Wheat Variety Performance Trial information to be ready on August 26. Refer to www.gocereals.ca for the latest updates.
Spring Cereals
Spring cereal harvest is just beginning and being delayed due to the frequent rain showers. Spring wheat yields have been average to above average so far. Quality has been variable. Some loads have good test weights, low fusarium, and good protein levels. Other loads have low test weights, protein levels, and high fusarium.
Harvest management recommendations are to continue to harvest as soon as possible, dry the grain to avoid storage problems, and reduce the risk of fusarium mould growth and resulting toxin production, and monitor stored grain closely for heating. Also, avoid selling wheat if quality is an issue, especially wheat graded “feed”, as prices are likely to improve. Be prepared to make every effort to upgrade wheat to grade three where possible.
Canola
Lodging of canola is a concern in some stands and some growers are contemplating swathing. In lodged stands, direct harvest in the direction of the crop lean will reduce shattering losses. Swathing should be considered if there is significant black pod spot or sclerotinia disease, as these will increase the risk of shattering. If the field is uneven in maturity, consider a dessicant to accelerate dry down, even ripening, and protect the grade. A dessicant, such as Reglone, or a pre-harvest herbicide, such as glyphosate, will not hasten maturity, but simply defoliate or kill less mature plants. Be prepared to harvest as dessicants lead to rapid dry down leaving the crop more vulnerable to shattering. Refer to product labels for timing and pre-harvest interval. If applying by ground, crop dividers can reduce tramping and shattering loss. A pre-harvest glyphosate application will assist with perennial weed control and dry down of weeds. The optimum stage to swath for both yield and quality is 30-60% seed colour change on the main stem. Also, check seed firmness. Under cool conditions, seeds near the top of the plant may continue to fill and become firm before the lower seeds begin to turn colour. Avoid swathing when a significant portion of the seed in the top pods, and side branches remain translucent and watery. Refer to the Canola Council ‘Time of Swathing’ guide at
www.canola-council.org/pub_swathing.aspx.
Optimum planting dates for winter canola in southwestern Ontario are August 25 - September 10. In other areas, aim to plant before September 1. For further information on growing winter canola, request the Winter Canola Guide from the Ontario Canola Growers or OMAFRA.
Edible Beans
Cranberry and early maturity white beans are turning rapidly. Yellowing in many later maturing fields is related to saturated soils, root rot, drainage and compaction.
Early infections of bacterial blight remained confined and have not spread as anticipated. Blight is favoured by high temperatures (above 28°C) and humidity. Leaf infection appears as brown necrotic areas on the leaf surrounded by a narrow, bright yellow margin. Pod symptoms may resemble those of other diseases, and should be combined with leaf symptoms or lab analysis. Infected seed develop a yellow discolouration that increases ‘pick’. There are no treatments available to control bacterial blight.
Bean leaf beetles are present in many fields at low levels. Thresholds for control have not been established for edible means, but the suggested threshold is the same as soybeans (-25% leaf feeding during pod fill, or 10% pod feeding). The economic level may be lower than this due to high crop value, and the importance of seed appearance. Be aware of days to harvest restrictions when applying insecticide.
If the field is intended for winter wheat and perennial weed pressure is high (e.g. milkweed), a pre-harvest burn-down may be the only option for weed control. Once beans are harvested, not enough top growth will remain to kill the weeds. Perennial broadleaf weeds such as thistles and milkweed can be controlled if application is made when weeds are actively growing and in the bud-to-flowering stage. Glyphosate will not be effective on some perennial weeds or annual weeds (e.g. ragweed, foxtail) that have already set seed, nor will the seed bank from these weeds be reduced.