Crop Report – April 13, 2023

Figure 2. Waterhemp seedlings (photo by Mike Cowbrough, OMAFRA)

Spring conditions have arrived across Ontario this week and some tillage and field preparation has started in fields with light-textured soils. Manure application is also underway. Taking a manure sample at the time of application is recommended and will help fine-tune fertilizer needs. Several heavy rainfall events in early April have some producers concerned about the amount of soil erosion occurring in many fields, even those with winter cover and with high residue and no-till practices. 

Winter wheat crops have come through the winter with good survival and stands appear thick with excellent tillering.  Nitrogen applications are beginning as the temperatures warm and fields dry. Nitrogen application is later than other years resulting in some debate about the value of split applications. There is increased interest in nitrogen stabilizers/inhibitors as the fertilizer prices remains higher than long term averages. The YEN program (Yield Enhancement Network) has increased the farmer-to-farmer discussion around management ideas and practices that lead to high yields. The importance of fertilization for high productivity was underlined by the project results.

Figure 1. Nitrogen application on winter wheat
Figure 1. Nitrogen application on winter wheat

Forage crops have broken dormancy with recent warmer conditions, and winter survival seems good. Doing a plant count is the “early warning system” to check how alfalfa has overwintered. The target number of healthy alfalfa plants per square foot varies depending on the age of the stand. Alfalfa stands thin naturally over time but can compensate because the crown of older plants is larger and sends up more shoots. If the stand does not meet the minimum plant count for its age, either overseed with clover or grasses, or terminate the stand. The nitrogen credit for corn is at least 100 lbs N/acre from a terminated forage stand with 50% legume content or more.

Corn acres look to be steady heading into planting season across the province. There is effort underway to better understand and improve nitrogen recommendations using a variety of tools and testing methods both new and old: 

  • Split application 
  • Pre-sidedress Nitrate Testing (PSNT) 
  • Delta yield estimates  

With fertilizer prices still well above a 5-year average, identifying the best rate that fits with specific management practices is still very important for the bottom line. A tool like’s Ontario Corn Nitrogen Calculator can help identify an economic rate. Go to to access this tool. 

Corn rootworm and corn borer resistance is increasing across Ontario. Scouting is important in counties across the province. Crop rotation and rotation of Bt corn hybrids that target the same pests will help prevent resistance. More information is available if corn rootworm or corn borer resistance is suspected.

Soybeans: Early planting indications are there may be less soybean acres this season, however some soybeans could be planted ahead of corn depending on soil and weather conditions. Early applications of hormone-based herbicides will help prevent off-target movement. Growers must keep an eye on the calendar and weather conditions so that when more summer-like conditions occur, dicamba is no longer an option.

Weed control: Dandelions, chickweed, purple deadnettle, and other common weeds are already visible in many fields. Waterhemp continues to make weed control a challenge, especially as its range increases across Ontario and now there are populations in the province that have evolved resistance to five different modes of action. Since 2015, waterhemp, which is spread by seed, has moved 800 km across the province. Dr. Peter Sikkema, University of Guelph shares a weed control goal to return zero waterhemp and fleabane weed seeds to the soil heading into spring 2023.

Figure 2. Waterhemp seedlings (photo by Mike Cowbrough, OMAFRA)
Figure 2. Waterhemp seedlings (photo by Mike Cowbrough, OMAFRA)

Waterhemp has many different biotypes, with different resistance profiles within a small geography.  The difficulty is knowing the resistance profile within specific fields, since the waterhemp may not be resistant to every active ingredient within a herbicide group. For example, CALLISTO herbicide applied POST gives 0 percent control of a 5-way resistant waterhemp while ACURON herbicide applied PRE gives 100 percent control even though both herbicides contain active ingredients from Group 27. More detailed information on waterhemp biology and control can be found at

Canada fleabane always requires two modes of action for control. 2,4-D, dicamba and Eragon are too inconsistent on their own. Eragon plus metribuzin is the basis for glyphosate resistant Canada fleabane control in IP and RR soybeans. To prevent yield loss, it is important to include soil applied herbicides to provide residual control.