We have been in several fields recently and are seeing a variety of issues. Excessive rainfall resulted in some crops going uneven and yellow. Most growers have been actively applying nitrogen to compensate for leaching losses. The colour of these crops is now improving.
On some farms, nematode injury to roots in sandier areas of fields has been observed. Root growth earlier in the season when it was cool and wet was less than it would have been had it been drier and warmer. As a result, nematode feeding on a plant with a less developed root system has had a greater effect than if the roots had been more actively growing.
Potato Virus Y (PVY) (click here for photo) continues to be seen in tobacco fields. Spread of PVY is primarily by aphids. Control of aphids in the tobacco will help to reduce spread of the disease from infected plants. Harvesting does not appear to spread the disease based on observations in past years.
Target Spot (click here for photo) is another disease that is being seen on farms. Protected areas of fields and lower areas of fields tend to be more infected. The lower leaves of the plant typically show the most infection. When several lesions are present on a leaf, the leaf will turn yellow and die. Further information about the disease and control of it can be found in OMAF’s tobacco publication.
Tobacco Mosaic Virus (TMV) (click here for photo) has been confirmed on a few farms. TMV is spread primarily by contact. Rogueing infected plants, provided the disease is not widespread, is often the best control to prevent spread to other plants. In fields where TMV is seen this year, it is not advisable to double-crop these fields next year. The disease is often much worse the following year in the same field if a host crop, such as tobacco, is grown.
To date there have been no reports of Blue Mold in Ontario. In the U.S., there was a recent report out of Virginia that Blue Mold was found on burley tobacco.
Topping has begun in earlier planted fields. Aphids and hornworms are active in several fields. Please follow the pre-harvest interval (PHI) with any product that is applied to the crop at this time.