Agronomists say crop growth stage, hail severity and recovery potential all influence final yield losses after severe weather in Manitoba.
Recent severe storms across Manitoba have left some producers facing damaged crops and uncertain yield prospects.
Hail ranging from loonie-sized stones to golf ball- and baseball-sized impacts was reported in several agricultural regions over the past week, damaging cereals, canola and other field crops. (Read: Manitoba Crops Under Pressure as Flooding, Hail and Excess Moisture Damage Fields.)
While hail damage can be alarming immediately after a storm, the provinces crop specialists say the full extent of losses often cannot be determined for several days.
The ability of a crop to recover depends on several factors, including hail intensity, crop type and the plant's stage of development when the storm occurs.
Wait Before Making Damage Assessments
Agronomists recommend delaying crop assessments for several days after a hail event.
Plants often require time to respond to injury, making immediate evaluations unreliable. Waiting allows producers to identify surviving growing points, assess regrowth potential and gain a more accurate understanding of likely yield impacts.
This approach can help producers avoid making premature management decisions that could unnecessarily reduce future production opportunities.
Wheat Recovery Depends on Growth Stage
Assessing hail damage in wheat can be particularly challenging.
When hail occurs during jointing or boot stages, plants may still be capable of pollination and grain fill. In some situations, new tillers can emerge and partially compensate for damaged stems.
However, yield losses generally increase as the crop advances through its reproductive stages. The greatest reductions typically occur when hail damages wheat during the milk stage, when kernels are actively developing.
Because each field responds differently, growers are encouraged to evaluate stand survival and recovery potential before estimating final losses.
Oats and Barley Often Show Strong Recovery
Of the major cereal crops, oats and barley are frequently among the most resilient following hail events.
Their ability to produce additional tillers allows them to compensate for damaged growth, particularly when storms occur before the boot stage.
According to Manitoba Agriculture, field experience has shown that barley severely damaged during the boot stage can still recover sufficiently to produce 70 to 80 per cent of normal yield potential.
When stems and green tissue remain intact, producers are often advised to leave the crop and monitor recovery rather than making immediate termination decisions.
Corn Damage Is Not Always Yield-Limiting
Corn often appears heavily damaged after hail because of shredded leaves and visible defoliation.
However, leaf damage alone does not necessarily translate into major yield losses.
The most important factor is whether the growing point and stem remain healthy. If the growing point survives, corn plants can frequently recover much of their productive capacity.
Between the V6 growth stage and tasseling, yield losses vary considerably depending on the percentage of leaf area damaged. Minor defoliation may have limited effects, while severe damage can significantly reduce final yield.
Producers are encouraged to assess both leaf loss and stem injury before determining the severity of impact.
Recovery Conditions Matter
Crop recovery following hail is influenced by more than the storm itself.
Warm temperatures, adequate sunlight and favourable soil conditions can accelerate regrowth and help plants overcome damage. Conversely, additional stress from flooding, disease, insects or nutrient deficiencies may reduce recovery potential.
With much of Manitoba already dealing with excess moisture this season, producers will need to closely monitor damaged fields in the coming weeks.
As crop development continues, careful scouting and follow-up assessments will provide the clearest picture of how much yield can ultimately be preserved following this season's hailstorms.
Download the document How to Asess Corn after a Hail Event from Manitoba Agriculture.