Heavy hail and young canola. While individual plants may die, a whole canola crop at the seedling or early-leaf stages is fairly resilient to hail when it comes to overall yield potential. At the 6-leaf stage, plants that lose most of the leaf area on the main stem can still live, but these leaves will not regrow. The plant will be delayed, and more of the yield potential — which will be lower than before the hail — will come from side branches. Read more.
Spraying for blackleg after hail. Blackleg infection in young canola plants is more likely to cause yield and economic loss than infection at later stages. Hail damage early in the season can increase the risk, and fungicide can help prevent severe blackleg in high-risk situations. The ideal time to apply fungicide for blackleg is no later than the 2- to 4-leaf stage – the earlier the better. Hail can set crop back to that stage if a lot of leaves are removed. Keep in mind that if the crop was at high risk for blackleg infection prior to the hail event, plants may have already been infected. Using a fungicide will reduce the risk of further infections, but will not “cure” any previous infections.
Rescue treatments. If a lot of leaf mass has been knocked off, nutrients in these leaves are unlikely to mineralize this crop year. So if crop recovery is strong, an in-crop nitrogen application can replace the nitrogen already taken up in this lost leaf mass. Results will be better if nitrogen supply was already low to moderate. Keep in mind that added nitrogen can also extend maturity, so consider the calendar date and crop stage with an eye on fall frost risk. Growers often look for other rescue treatments to revive the crop and save what’s there, but nothing is proven to work consistently. If you have suffered losses from a hail event and are considering a rescue treatment, leave check strips or consider UCC’ing this field. Link to Ultimate Canola Challenge (UCC) protocols for on-farm trials