Over the weekend, a Norfolk County grower found a few Envol plants infected with late blight. The disease is under control; the affected plants were destroyed and the field sprayed with Ridomil plus Bravo. Most of the reports of late blight from the United States have been US 23, the tomato strain. US 23 is, so far, sensitive to Ridomil.
There are still many fields in the province that are green and may need three weeks to reach the finishing line. It is critical to keep your fields free of late blight at the end of the season. Monitor them closely, especially risky areas in fields such as:
- Low lying areas that tend to be wet for long periods after rainfall.
- Compacted areas.
- Rows close to tree lines.
- Field edges along creeks or ponds.
- Pivot center points and pivot wheel tracks. Look closely at the plants under the first tower of center pivots. This area remains wet longer than areas farther out on the boom. Also, wheel track areas usually remain damp or wet after other parts of the field have dried up.
- Weedy areas.
- Windward sides of fields. Windborne spores may blow in and infect here.
- Any area that is protected from the wind where leaves tend to remain wet longer.
Keep fields protected with fungicides specific for late blight. Add Kocide or Parasol to the tank mix to reduce the risk of tuber infection.