Included: Freeze injury, glyphosate resistant weeds, weed control, wheat disease, soybean seeding rates.
Synopsis: Extremely cold temperatures over the weekend caused widespread damage to fruit trees, etc. Temperatures as low as -8 C were measured with one report of -10 at ground level (Norfolk county). Weekend low temperature maps are available at http://www.weatherinnovations.com. Wheat, alfalfa and pastures were damaged and injury is beginning to show. Widespread rainfall yesterday ended field work for now. Most areas received ¼ to ½ inch of light rain. The rainfall was gentle and slow. This was excellent for the crops seeded into dry conditions and for overworked fields. Growth has continued to be slow due to cold temperatures: forecasts of warmer temperatures should improve growth. From April 1 to May 1 there were about 180 CHU’s accumulated in the south but only about 100 CHU’s in theExeter area. Corn planted 4 weeks ago is just starting to spike. Corn planted on April 16 has a ¼ inch sprout. Rainfall in April was about ½ the usual amount or less. With good soil conditions and no crusting to date emergence is expected to be good.
Glyphosate resistant ragweed has been confirmed in the Napanee area. Glyphosate resistant Canada Fleabane is suspected in the Niagara area. This is a good reminder that good glyphosate stewardship is important for Ontario agriculture. Don’t just spray glyphosate! Use different modes of action.
Corn: Corn planting ranges from as little as 10% in the north to 95% complete, depending on the region. The Exeter area is essentially finished. Excellent ground conditions all spring except that some fields got too dry. Rain yesterday was perfect for those fields. Larger growers have finished planting corn and have switched to soybeans. It’s estimated that 50-60% of the crop has been planted in the province (35% for Eastern Canada). A few producers are still deciding on what to plant for the last few fields. Strong soybean prices will shift any swing acres to soybeans (less than 5% switch overall). The market is using price to buy soybean acres. Corn seed in every heat unit range is still available, but hopefully no replants will be necessary. No freeze injury on early planted corn has been reported to date.
Tillage: More rollers have been used this year. Under dry conditions rolling will help draw moisture to the surface. This has been a good decision this year. Rolling also buries stones and allows lower combine header cutting in soybean fields. Rolling can cause soil consolidation issues and crusting problems if heavy rainfall follows planting. So far this has not been a problem in 2012.
Winter wheat: Ongoing cold temperatures and frequent frost have damaged wheat plant tissue. Weekend freeze damage looks to be on leaves only in the vast majority of fields. Literature suggests that -4C for 4 hours will cause head injury to wheat at this stage: very little head injury has been observed so far (Hay swamp, Mn deficient areas only). Expect a lot of scorched leaf tissue to show over the next few days. In the southwest the wheat has looked good but further north with more frequent and colder temperatures the wheat has suffered. There are large differences in wheat development dependent on planting date and location. Some fields are just at stem elongation while others are at flag leaf.
Very little wheat has been sprayed with herbicides because of cold temperatures. Annual weed pressure has been low this year. There may be another flush of annual weeds but the wheat is far enough advanced that these weeds will not impact yield. Paybacks on herbicides in winter wheat are usually small although the fields are much cleaner at harvest and it offers another chance at resistance management. There is a significant difference in weed pressure in fields that had a glyphosate application last fall. Fields that received glyphosate last fall are very clean compared to fields not sprayed. Trial work from the University of Guelph, Ridgetown Campus, has shown that ½ rate of Refine in the fall controls chickweed the following spring. Chickweed control in the spring can be difficult.
Foliar disease has been minimal to date but moisture and warmer temperatures this week could change that quickly. Frosted wheat with necrotic tissue does not necessarily respond more to foliar fungicides. Foliar diseases feed on living tissue, and frosted leaves are not more susceptible to disease.
Tile run wheat continues to be evident. Wheat this year has been an excellent advertisement for tile drainage.
Soybeans: Approximately 5% planted. Soybeans planted two weeks ago have shown little growth to date. Once fields dry planting will start in earnest. There is no reason to wait at this date even if soil temperatures are cool. The yield benefit of early planting generally outweighs the risk of planting into cold soils.
Burndowns should go on immediately: in fields worked early that are planned for “stale seedbed” planting a burndown may be necessary. Even though fields look clean small weeds will start to emerge with warmer temperatures. Fields that received minimal tillage (vertical tillage) should receive a burndown application first. Vertical tillage is not adequate to kill all weeds.
Seeding recommendations are significantly lower in some US states. US recommendations are based on using a planter, with more heat units than Ontario. Ontario seeding rates are based on 45 replicated trials from 2005-2007. The most economic seeding rates for are:
- 194,000 seeds/acre in 7.5” rows.
- 177,000 seeds/acre in 15” rows with a drill and
- 165,000 seeds/acre in 15” rows planted with row unit planter.
It is possible to achieve high yields with lower seeding rates but plants must be evenly distributed and field conditions ideal. In dry years with short plants very low plant stands can significantly reduce yields.
Forages: New seeding alfalfa and red clover underseedings look to have survived the weekend freeze. Some red clover stands are very disappointing from dry weather and repeated freeze events. Established alfalfa and orchard grass stands have been significantly set back again by the weekend freeze. This will delay maturity, and coupled with the March 30th freeze, will reduce first cut yields.
Crop Insurance deadlines:
May 1: New applications and coverage changes
June 15: Last day to report unseeded acreage.
June 30: Spring seeded final acreage reports due.
July 10: Premiums due.
Chair for this meeting was David Townsend. Thanks for keeping us on time. Chair for next meeting will be Barry Gordon.
Publication 812 – Field Crop Protection Guide is available at any resource center, or by calling ServiceOntario Publications, 1-800-668-9938 or 416-326-5300.
CropLine – 1-888-449-0937
CropPest Website – http://www.omafra.gov.on.ca/english/crops/field/news/news_croppest.html
Stratford Crop Technology Contacts:
Horst Bohner, 519-271-5858 or firstname.lastname@example.org
Peter Johnson, 519-271-8180 or email@example.com