Forage Focus 2019: Winterkill Woes – What we can learn from 2019
On December 5 the Ontario Forage Council’s annual Forage Focus Conference and Trade Show was held in Stratford, and was live streamed to remote locations across the province including Earlton, Cochrane, Timmins, Emo, and Verner. The theme of the conference was “Getting the Most From Your Forage Investment.” The first speaker of the day was Christine O’Reilly, OMAFRA Forage/Grazier Specialist; whose talk was entitled “Winterkill Woes – What we can learn from 2019”.
In her presentation O’Reilly addressed the challenging growing season experienced in many parts of the province, and some lessons that could be taken from it. The weather problems that affected this season actually started last winter, when surprise thaws melted the insulating layer of snow that protects fields, and then that meltwater subsequently froze into icesheets that smothered forage. Heavy snows over the winter resulted in heavy meltwater in the spring, and coupled with significant rainfall, many fields were drowned, delaying forage growth.
With conditions like that, O’Reilly stressed the importance of field assessments in the spring, once plants had an opportunity to get started. For alfalfa, once plants begin to green, a stand count can be done as an early warning system for yield quality. This is done by counting the number of alfalfa plants growing per square foot in a field. Plant count benchmarks for alfalfa depend on the age of the seeding. A new seeding should have 20 or more plants per square foot, a year old seeding: 12-20, 2 years: 8-12, 3 or more years old: 5. This is a rough system for measurement, and must account for other forage plants in the stand and the needs of the producer, but in general if an alfalfa stand falls below the above benchmarks it is a predictor of low yield potential and replacing the stand could be considered.
A more accurate field assessment option becomes available later, when alfalfa has had time to grow to a height of about 15 cm or 6 inches. At this point, a stem count can be done, which is a more accurate predictor of yield than the plant count because older plants send up more stems than newer plants do, which provides a higher yield. A stem count is done by counting the number of stems coming up from the plants within a square foot. If a count results in 55 or more stems per square foot, that is indicative of a high yield potential of up to 100 percent. A stem count of 40-50 has a potential yield of 75 to 92 percent, generally worth keeping for that year but possibly worth reseeding the next spring. Stands of less than 40 stems per square foot indicate a poor yield potential of below 75 percent, and that’s before any weather or pest issues that could happen later in the year to further reduce yield. Generally, with a stem count of less than 40 the producer should consider terminating the stand and replanting.
The frustrating thing about poor weather is that it’s out of the hands of the farmer. No one has control over the rain, but there are some things that O’Reilly suggests farmers can control to improve their fields. The first suggestion is to select an alfalfa that has a high resistance to diseases. This is the best way, right off the bat, to reduce a potential stressor to the plant.
The second controllable factor is soil fertility. Soil testing should be done frequently to determine what the field needs, and then fertilizers should be applied to meet that need. O’Reilly notes that often forage fields are left out when fields with other crops are fertilized, but that forage should be fertilized as well in order to reach its maximum potential. For alfalfa, potassium levels are very important as they help the plant survive the winter, and should be monitored.
The third controllable factor is respecting the rest period for plants in the fall. During fall, a plant starts to sequester energy in its roots that it uses to re-grow in the spring. For alfalfa, the rule of thumb is that the fall rest period is the six weeks before the first frost of the fall. Estimations for the beginning of this period can be found on the map below. O’Reilly says that it can be tempting to harvest or to pasture animals on the alfalfa during the rest period, but that if harvest or grazing is put off until after the first frost, then the plants will not try to regrow in the fall and will conserve those stored resources to get a batter start in the spring. If harvest or pasturing can’t be put off until after the frost, then the middle of the fall rest period should be avoided. The middle is estimated to be three weeks after the date shown on the map below. Harvesting or pasturing either towards the beginning or end of the rest period is better than the middle, but still has the potential to negatively affect spring growth more than waiting until frost.
A final controllable factor is doing field scouts to assess for problems. O’Reilly uses the example of Potato Leafhopper insects, which were found across Ontario in alfalfa. The solution for Potato Leafhopper, if already established in the field, is to cut the forage, which is hopefully mature enough to use as feed. Cutting the forage serves two purposes, it takes away the food source for the insect and it encourages new growth in the alfalfa, which may surpass yields if Potato Leafhopper had already damaged existing growth on the plant. Potato Leafhopper has a compound in their saliva that stunts the growth of plants, so at the point of infestation spraying has little effect because the yield is already reduced. O’Reilly recommends cutting the field, then 5-7 days after the cutting, scout the field again and assess the number of insects. If it’s still too high, then spraying can be considered.
In conclusion, O’Reilly stresses that the best way to protect your forages is to be proactive, and the best way to be proactive is to scout early and scout often. This will allow you to ensure your fields are growing well and you can get ahead of any productivity, pest, or disease problems.
Stay tuned for more articles about the Forage Focus 2019 conference.