Current weather conditions are ideal for fusarium head blight development in winter wheat. Many wheat fields in Southwestern Ontario have applied a T3 fungicide to reduce their risk particularly if they are growing a FHB susceptible variety. T3 fungicide applications further east will begin this week and continuing into next week for Eastern Ontario. A number of fields saw increased stripe rust pressure over the weekend. Growers with fields that were a few days away from a T3 application opted to wait and spray for both stripe rust and fusarium at the T3 timing. Some fields received an early heading fungicide application if they were a week or more away from a T3 fungicide application and growing a stripe rust susceptible variety to reduce the impact from stripe rust. Those fields will then receive a second fungicide application at pollination for protection against fusarium if needed. Refer to the OMAFRA Field Crop Protection Guide, Publication 812 when selecting fungicides for stripe rust and fusarium head blight control. There have been reports of leaf tip necrosis starting on the flag leaf and moving down in fields. This leaf tip necrosis is likely associated with a specific or group of disease resistant genes and is the plant’s response to the presence of disease such as stripe rust. The yield impact from this is minimal.
Early spring cereal fields are at tillering (GS24) and continue to look good. All weed control applications should be wrapping up shortly.
Corn planting is essentially now complete. With the exception of corn silage or some growers in long season regions, most unplanted fields will now likely be switched to soybeans. If corn herbicides have been applied but corn could not be planted, work with your herbicide provider to determine next best cropping steps. Overall corn is progressing well with a large amount of crop at the 2-3 leaf growth stage, with early planted corn beyond that. Minimal corn replants have been reported to date. Some sidedressing is now underway. There have been reports of black cutworm and slug feeding in a number of fields as a result of delayed crop planting and emergence and cool, wet weather conditions. There have also been reports of corn turning purple or white as a result of stress but those fields are expected to grow out of this.
OMAFRA Field Crop staff began tracking soil nitrate levels at a number of sites across the province the first week of May. Initial results suggest that soil nitrate levels are lower this year compared to previous years. Conventional PSNT timing sampling is being completed this week. Results will be posted at Weathercentral.ca under “Corn – GFO Nitrogen Research” (http://bit.ly/1rd6z3F ) as they are made available.
Soybean planting is 80% completed across the province with some areas further behind compared to previous years due to significant rainfall this spring. The crop ranges from the hook stage to unifoliate growth stage. There continues to be weed challenges in a number of fields that did not receive a pre-plant burndown. Weed control during the early stages of soybean growth is critical. When making herbicide spray decisions pay attention to the growth stage of the weed as well as the growth stage of the soybeans.
There have been damage reports and replants particularly in Lambton, Essex, Niagara and Haldimand counties where they have received large amounts of rainfall and crusting became an issue. When doing plant population assessments a stand with 100,000 uniform plants per acre should not be considered for replanting. Research has shown that 100,000 plants per acre has a 98% yield potential on most soil types. On heavy clay soils 110,000-120,000 plants per acre are necessary for maximum yield potential. Rolling fields after the soybeans have fully emerged compared to rolling immediately after seeding helps alleviate stand losses due to crusting (Figure 1). Rolling can be up done up to the 1st trifoliate stage. There have been reports of seed corn maggot feeding in a number of regions due to the cool, wet weather (Figures 2 & 3). Fields planted without Class 12 insecticides that have sufficient stand loss due to certain soil insects including seedcorn maggot may warrant the completion of Inspection of Crop Pest Assessment by a Professional Pest Advisor. If stand loss thresholds for the Class 12 regulations are reached, Class 12 insecticides can be purchased for that farm property. Contact a Professional Pest Advisor and refer to https://www.ontario.ca/page/neonicotinoid-regulations for more information. Bean leaf beetle feeding has also been reported in Essex County. Fields planted with fungicide-only seed should be scouted during the early seedling stages. Spray is warranted if 16 adult beetles per 30 cm of row are found on VC to V2 stage soybeans. If plants are clipped off at the stem, control is warranted if adults are still present and actively feeding.
First-cut alfalfa has begun in many areas with excellent yields being reported to date. Growers who applied some early season N to forage stands are reporting significant yield boosts. Alfalfa weevil and potato leafhoppers have been present in some areas. Refer to the OMAFRA Publication 811, Agronomy Guide for Field Crops for more information on scouting and threshold guidelines.
Canola emergence has been good to date; however, crop advancement has been slow particularly in northern Ontario. The earliest planted fields are at the 4 leaf stage. Growers in the Timiskaming area are already catching swede midge at this time and are likely going to have to spray sooner than anticipated. Swede midge has also been caught in the Shelburne area but has not yet reached thresholds. Due to the later planted crop and swede midge emergence this year it is anticipated that swede midge feeding will be a significant challenge. There have also been reports of high flea beetle pressure in some fields. Refer to the OMAFRA Field Crop Protection Guide, Publication 812 for swede midge and flea beetle management options.
Due to the excessive moisture in many areas, edible bean planting is approximately 15% complete. It is expected that the remaining acres will be planted later this week once conditions dry up.
Table 1. May 31 – June 6, 2017 Weather data