Now that the in crop weed spraying is complete, it is time to think about disease and insect spraying. It sure seems like a never ending cycle, and to boot, you have to hope that the white combine misses all your crops! This can make for a very stressful time of year. Hopefully this can shed some light on what to look for when you are out in your canola fields, whether it is staging for disease or sweeping for insects.
Sclerotinia stem rot is a major disease in canola. I am sure a lot of you have seen and can recognize the symptoms, but at that time, it is too late to do anything about it. With these very favorable field conditions that we have, it is the “perfect storm” for Sclerotinia. Your canola plants are most susceptible to damage at early flowering because the Sclerotinia spores must contact the flower parts first in order to cause infection. Once these infected petals fall off and into the stem axis, they start to decay and the infection moves into the stem of your canola. This can lead to premature ripening and pale green or white lesions on the stem and branches. These straw colored plants are very easy to spot in contrast with the other green and healthy plants. There are a couple things that you can do in order to help control this disease, a four year canola rotation is recommended to break the disease cycle, or you also have the option to apply a registered fungicide. When you are staging your canola for the optimal time to spray it is when the crop is at 30-50% bloom. This is between 20-35 flowers on the main stem. It is important to watch for this disease, since the Sclerotinia fungus can survive in the soil for up to four years!
It is still early to be sweeping for insects, but it’s time to start thinking about it and keeping it in the back of your mind, since it is only about a week away! Some of the insects you might come across this season are lygus bugs, diamond back moth larva and cabbage seedpod weevils, just to name a few. The threshold levels vary with each pesky little critter!
On July 5th, we scouted the canola plot to see how it was growing, did plant counts, and see if there were any early arrivals of insects. Generally speaking, the emergence was fine and some divergence between the varieties could already be observed. Overall, buds could be seen in each strip, and some varieties were bolting faster and higher than others. The variety that stands out in the plot is both of Dupont’s, 3151 and 3152. They are a length ahead of the other varieties, have more buds and also have started to flower.
During our visit to the plot, we also take the opportunity to scout for insects. Lygus bugs, diamondback moth larvae and cabbage seedpod weevils were found, but they were not close to reaching the threshold requiring a treatment.
We hope to see all of you at our 2010 Get More Bushels Super Crop Plot Tour on Wednesday July 21, 2010!!