The first Sclerotinia risk map for the 2016 season will be available on June 20th, 2016 at three different websites, the NDSU Canola Pathology program, the Northern Canola Growers Association, and the Minnesota Canola Council. The Sclerotinia risk calculator will be available only at the NDSU canola pathology website. Both, the risk map and the risk calculator were designed to help growers determine if environmental conditions are favorable enough for white mold that a fungicide application is warranted. The risk map and risk calculator are only applicable when canola is in bloom. The user-friendly tools were developed by canola pathologist Luis del Rio at NDSU with funding from the Northern Canola Growers Association.
How they work. Canola petals are necessary for infection by Sclerotinia ascospores to occur. From colonized petals, the fungus spreads to healthy green tissues and eventually, large yield-robbing lesions will develop on the stem and branches (Figure 1). However, infection only occurs if conditions are favorable; adequate rainfall before flowering and cool to moderate temperatures with long wet periods during flowering will promote infection.
The Sclerotinia risk map is created from weather data collected from NDAWN weather stations to determine if conditions are favorable for white mold. Green, yellow and red areas signify areas of low, medium and high risk.
The Sclerotinia risk calculator uses the same data collected from NDAWN, but also takes into account additional data that growers can enter into the site. The additional data adds personalization and precision to Sclerotinia risk forecasts and is especially helpful when fields are in areas of intermediate risk.
Two words of caution. First, canola is only at risk during flowering and consequently the Risk Map and Calculator are only applicable during flowering. Secondly, the maps are only as good as the data received from NDAWN. If you know that your fields have had more (or less) rain that the nearby station your risk may be higher (or lower).
Extension Plant Pathologist, Broad-leaf Crops
Luis del Rio
Larvae of the diamondback moth and imported cabbage moth have been observed on canola fields near Langdon in Cavalier County.
Diamondback Moth and Cabbage Moth Found in Canola
Larvae of the diamondback moth and imported cabbage moth have been observed on canola fields near Langdon in Cavalier County. Both larvae feed on the leaves causing defoliation and holes in leaves. Feeding injury by diamondback moth larvae have a characteristic windowpane effect and small, irregular-shaped holes. Larvae of diamondback moth are lime green and about ½ inch long with a forked posterior end. When disturbed, larvae thrash backward violently and often drop from the plant, suspended on a strand of silk. Larvae of the imported cabbageworm also are lime green with a white line down the side and about 1 inch long and larger. It develops into a cabbage butterfly as an adult. Both larvae are cryptic ‘green’ and blend in with the canola leaves making them difficult to see.
It is important to note that these species of larvae are present in the canola crop; however, significant damage is caused by the subsequent generations that emerge later during flowering and pod development. For diamondback moth, larval feeding on flower buds and flowers causes flowers to abort, and can results in the most significant injury and subsequent yield loss, especially during drought (not current conditions in northeast area). There are usually not high enough numbers of imported cabbageworms to cause yield loss in canola in North Dakota. In Canada, they have observed 8-10 larvae per plant without needing to spray, because parasitism rates are usually high in imported cabbageworms.
For diamondback moth, scout fields as we get closer to flowering by pulling up canola plants from a square foot and beat them in a white bucket. Then, count the number of larvae dislodged from plants. Larvae often will dangle from canola plants on a silk thread. Repeat this procedure in at least five locations in the field to obtain an average of the number of larvae per square foot. The economic threshold is based on larval densities of:
- Flowering: 10 to 15 larvae per square foot;
- Pod stage: 20 to 30 larvae per square foot.
Anitha Chirumamilla & Janet Knodel
Register now for the Northern Canola Growers Association Golf Tournament to be held July 21st, 2016 at the Langdon Country Club. Registration for the 4-man best ball tournament is $50/player or $200/team. You may register individually and be placed on a team or register a complete team. The registration fee includes 9 holes of golf, a cart to be shared with one of your teammates, refreshments, and supper at the club house. Many prizes will be awarded. Registration for the Langdon tournament is limited to the first 132 players, so register early! This tournament is made possible by the support of our industry sponsors. *Fax, Email or Mail back Registration form and payment to secure your spot!
Northern Canola Growers Association
125 Slate Drive Ste. #4
Bismarck, ND 58503