Field Observations

A cool, wet, and in some cases, snowy spring has so far delayed many field operations.

Wheat

Scouting whether to keep or terminate a wheat field has been ongoing in various areas. Some fields are looking quite good, while others are struggling due to late planting, heavy rains after planting, and, in some cases, snow mould. A quick lesson on assessing wheat stands can be found here .

Fields planted early last fall tillered nicely before winter and are well established this spring. These fields do not necessarily need an early application, but can benefit from an N application as the season progresses. The best timing is before the plants start to stem elongate; however, keep in mind that application timing can be affected by when fields are dry enough to carry the equipment without causing field damage (rutting). It’s important to check the weather forecast and walk the fields to check the growth stage of the crop.

A delay in N application can result in the crop showing signs of deficiency. The yellowing of wheat due to a lack of N in the soil is a sign of crop stress. Early stress on the crop will cause fewer florets to develop, which means fewer kernels, and a lower yield.

It’s also important to note that a herbicide application needs to occur before stem elongation to prevent damage to the plant and head development. Any stress just before, and during, stem elongation can cause damage to the developing head and reduce yield potential. Scout early, and scout often for plant growth, weeds, and diseases.

Following your wheat crop along, and timing crop protection and nutrient applications is important for optimizing yield. The visual guide to winter wheat staging is a handy tool for identifying what growth stage your crop is at!

Insects

As we approach planting, insect pests should be monitored, as they may affect crop stands. In some cases, the insect larvae can cause significant reductions in stands and early season plant vigour. High-risk fields are those that are being planted early, following hay or grass, fallow, or a grassy cover crop. If the spring continues cool and wet, it will be favourable to early season pests. Learn more here .

Weeds

We recently received some insight from Mike Cowbrough, OMAFA’s weeds specialist, about the weed spectrum in Ontario, and what growers should be aware of.

Cowbrough shared, “Both the number of herbicide-resistant weed species in Ontario, and the number of herbicide groups to which those weeds are resistant, continue to increase over time. This is almost inevitable, as intensive and repeated use of the same herbicide modes of action increases the likelihood that weed populations will evolve resistance.

Fields planted early last fall tillered nicely before winter and are well established this spring. These fields do not necessarily need an early application, but can benefit from an N application as the season progresses. The best timing is before the plants start to stem elongate; however, keep in mind that application timing can be affected by when fields are dry enough to carry the equipment without causing field damage (rutting). It’s important to check the weather forecast and walk the fields to check the growth stage of the crop.

A delay in N application can result in the crop showing signs of deficiency. The yellowing of wheat due to a lack of N in the soil is a sign of crop stress. Early stress on the crop will cause fewer florets to develop, which means fewer kernels and a lower yield.

It’s also important to note that a herbicide application needs to occur before stem elongation to prevent damage to the plant and head development. Any stress just before and during stem elongation can cause damage to the developing head and reduce yield potential. Scout early and scout often for plant growth, weeds, and diseases.

Following your wheat crop along and timing crop protection and nutrient applications is important for optimizing yield. The visual guide to winter wheat staging  is a handy tool for identifying what growth stage your crop is at!

Insects

As we approach planting, insect pests should be monitored as they may affect crop stands. In some cases, the insect larvae can cause significant reductions in stands and early season plant vigour. High-risk fields are those that are being planted early, following hay or grass, fallow, or a grassy cover crop. If the spring continues cool and wet, it will be favourable to early season pests. Learn more here. 

Weeds

We recently received some insight from Mike Cowbrough, OMAFA’s weeds specialist, about the weed spectrum in Ontario, and what growers should be aware of.  

Cowbrough shared, “Both the number of herbicide-resistant weed species in Ontario and the number of herbicide groups to which those weeds are resistant continue to increase over time. This is almost inevitable, as intensive and repeated use of the same herbicide modes of action increases the likelihood that weed populations will evolve resistance.

“Additionally, the introduction of new weed species from other regions that already carry herbicide resistance, such as Palmer amaranth, is something we have seen recently in Ontario. In some cases, crops used as cover crops become problematic weeds themselves, for example, Italian ryegrass, which is widely used as a cover crop, turfgrass species or forage grass species, now has confirmed glyphosate-resistant (Group 9) populations in Ontario, making it much more difficult to control.”

Mike was also asked if there are any trends of particular significance for Grain Farmers of Ontario and relayed the following:

1) The increased prevalence of group 14 resistant weeds – pigweed, waterhemp and common ragweed

2) Increase in prevalence of glyphosate resistant ryegrass

Weeds resistant to multiple herbicide modes of action are increasingly common, and this is especially concerning since there are not many options available to manage such species.

Multiple-herbicide-resistant waterhemp is the clearest example. In Ontario, waterhemp populations have evolved resistance to five herbicide groups (2, 5, 9, 14 and 27), and herbicide-resistant waterhemp has been confirmed in 19 counties from Southern Ontario to Northern Regions.  Multiple resistance is also very common in other key species relevant to growers and their rotations, including common ragweed, green and redroot pigweed, and Canada fleabane.

Palmer amaranth is not yet widely established in Ontario, but it is widespread in field and vegetable crops in the United States and is associated with severe yield losses. Our recent work has detected Palmer amaranth populations in Lambton and Stormont, Dundas and Glengarry in 2025. This species is extremely competitive and is known globally to have evolved resistance to nine different herbicide groups, with populations documented that are resistant to up to six herbicide modes of action simultaneously.”

Stay alert and scout fields for problem weeds and manage them effectively this spring. If there is a weed that is hard to identify or has not reacted to herbicide applications as you think it should, ask your local agronomist for a second opinion.  If there are still concerns, weed resistance testing is available in Ontario.  A resistant weeds dashboard is also available to better identify which weeds may be more challenging to control regionally across the province.

Crop Protection Hub

The Crop Protection Hub is a wonderful resource for management strategies for weeds, disease and insects. It also provides Ontario farmers with up-to date information about registered products and Integrated Pest Management approaches to crop protection. Explore the hub here.

Avian Influenza

Biosecurity when travelling from field to field is important to keep in mind, as avian influenza is often present in the area each spring. Ensuring you don’t step in bird droppings, staying away from poultry barns, and thoroughly cleaning your boots and field implements when moving from field to field are always good practices. More information on biosecurity tips can be viewed here.