Knowing your plant stand is the best way to understand how your fields should be managed for the rest of the season. It will also help in managing your seeding rate for the future.
“Plant counts can determine whether your seeding system and seeding rate have given the crop the best start,” says Canola Council of Canada senior agronomy specialist Derwyn Hammond.
Stands of 10 plants per square foot (100 per square metre) are ideal as they provide a cushion for loss due to frost, diseases or insects. Stands of less than four or five plants per square foot (roughly 40 to 50 per square metre) generally cannot reach their full yield potential.
If the plant stand is less than 10, Hammond advises checking equipment settings, seed characteristics and field conditions to identify why they did not achieve the ideal plant population. Was it directly related to the seeding operation or was it environmental factors such as frost, wind or flooding, insects or disease?
Recording the average number of plants per square foot also helps growers improve their seeding methods for 2011. “You can keep records of thousand seed weight, seeding rate and seeding date, plus seeding depth and soil temperature, but what’s the point if you don’t also do plant stand counts?” says Hammond.
Plant stand assessment is also essential information for setting seeding rates in the future. Growers who usually achieve above 10 plants per square foot under average conditions may have been able to trim costs with a lower seeding rate. But if plant populations are routinely at seven plants per square foot or less, reducing rates could spell trouble.
Knowing how plant density is distributed for each field is valuable information as well. For example, if the stand is spotty and thin, growers should consider extra vigilance and be more conservative with thresholds for insects, weeds and diseases.
HOW TO DO A PLANT COUNT
Growers can use hoops equivalent to one-quarter of a square metre, placing the hoop into the crop, counting the number of plants inside, and multiplying by four to get plants per square metre. Several counts per field are required to get a good average. Growers considering reseeding should take 50 to 100 samples to be sure it is the right manage approach.
Growers can make their own 50 cm by 50 cm (quarter-metre) square or make a hoop with an inside diameter of 56 cm, which is the equivalent of a quarter-metre square.