Manitoba Agriculture, Food and Rural Initiatives
Manitoba Weekly Vegetable Report
| Carrots | Cole Crops | Corn | Cucurbits | Onions | Others |
Introduction
Rain, rain, clouds and rain were the story for most of the past week, which was not welcomed at this time of year. Harvest operations have been delayed, as even our scouting personnel were sinking is some very wet fields. As a result this weeks scouting report is rather short, due to the challenges of not only getting to fields but actually walking through them.
Carrots
Carrot harvesting in our scouted fields began this week, before the weather intervened. Carrots harvest will likely begin/continue in all of our scouted fields (weather permitting) next week. Ideally harvest will be completed by October.
Some minor reports of aster yellows are coming in with questions of why we are seeing them as we have been reporting very low numbers of leafhoppers. It is those very low numbers of leafhoppers we mention that are transmitting the phytoplasma to the plants. On a large scale, there will likely never be a field completely free of the symptoms of aster yellows. We have a few individuals that overwinter and survive here and there is plenty of phytoplasma to pick up in non-carrot host plants, so some will always be present. The amount that is present would have probably showed up even if a grower were to spray every week. It just doesn't take that much to have a plant show symptoms, so if a single leafhopper escapes a spray, you will see symptoms. Our point is merely that the levels were not economical this year so spray controls should have been used sparingly as the pressure was small, especially when compared to last year.
No other diseases of carrots were observed this
week.
AYI is calculated by taking the number of leafhoppers and multiplying this by the infectivity level below. The migrating aster leafhopper population infectivity in Wisconsin is 4%. This is slightly higher than the normal 0-2%.
| Crop | AYI |
| Carrots | |
| Resistant (eg. Six Pak II) | 100 |
| Intermediate | 70-75 |
| Susceptible (eg. Spartan Bonus) | 40-45 |
| Celery, Romaine | 30-35 |
| Head Lettuce | 20-25 |
Cole Crops
Cabbage, cauliflower, and brocolli have been harvested or are going to be finished in the next week (again weather permitting).
There can be a number of storage rots that can cause problems to these crops, but few have come to our attention this year. On the whole, disease wise this not a terrible year for brassica crops.
Corn
Sweet Corn continues to be harvested, and may be completed by the time report goes up. We were unable to get to our sweet corn field this week.
This year there were more diseases of concern in sweet corn than usual, but while they generated excitement when they appeared, the damage was minimal.
Cucurbits
Pumpkins, cucumbers are being harvested, some pumpkins are still ripening, as noted last week, in general this will be a "small" pumpkin year.
Cucurbits were almost completely disease free, typically powdery mildew shows up about now, but we have not detected any.
Onions
Onions have been pulled in some fields, there have been other fields which were facing sizing issues.
As onions are often left to dry down in the field the wet weather was the last thing mature onions needed. Botrytis fungi need to attack succulent, living tissue. There have been a number of soil line rot samples this year, but the concern is due to Botrytis allii, the cause of neck rot. If the onion necks have dried down enough (assuming the fungus hasn't already entered), then this season could be a good one. Neck rot shows up after harvest, and remains a major problem in Manitoba onion production.
Others
Most red beets have been harvested, sizing up of the last plantings continues, the return of warm weather would be welcome.
No diseases to report at this time in red beets.
Prepared by:
Brent Elliott Entomologist Ph.
204-745-5669
Philip Northover Pathologist
Ph. 204-745-5694 Manitoba Agriculture, Food and Rural
Initiatives, Crops Knowledge Centre, Carman
