The crop continues to progress quite well. Topping has begun on some farms. Recent rains and warmer weather have helped to push out the buds in the earlier plantings. Leaf counts of topped tobacco on some farms have been reported to be in the 18-19 range. Aphid pressure is beginning to increase in several fields.  Hornworms are also being found in most fields. To date, there are no widespread problems being reported and there have been no reports of Blue Mold in Ontario.

Beginning last week, we started to see Potato Virus Y infected tobacco plants in certain fields. This is about 2 weeks later than the first reports in 2013, however, it is still earlier than when we typically see the first symptoms of the disease in late July/early August. For detailed information about PVY, please refer to the technical bulletin entitled “Tobacco Pests and Disorders in the Field – Potato Virus Y” posted in the plant protection section under the research heading of this website.

PVY infected tobacco plant.

Another issue being reported on some farms is Leaf Drop. This is where the midrib of the leaf breaks about 2.5 cm (1 in) from the stalk. Leaf Drop is often seen in the lower stalk positions, i.e. sands, seconds or thirds. Some varieties are more prone to this condition than others. In addition, stage of growth and environmental conditions are contributing factors. Leaf Drop tends to be greatest shortly after a rain or irrigation when the plant is close to the topping stage and conditions are hot and humid. High winds during the stage when the plant is vulnerable to Leaf Drop can increase leaf breakage.

Leaf Drop shown near bottom of plant.

Target Spot (Rhizoctonia leaf spot) is also being seen in some fields. Ideal conditions for this disease are extended periods of high humidity and temperatures in the 20-30°C range. Protected areas in fields tend to provide more favourable conditions for this disease. The lower plant leaves are more severely affected by Target Spot. Several lesions on a leaf can cause the leaf to breakdown prematurely. Further information about Target Spot and its control can be found in OMAFRA’s publications 842 and 843.

Target Spot

Weather Fleck has started to show up recently. This disorder is caused by certain oxidants in the air, mainly ozone, that cause spotting on leaves. Initially the spots are usually less than 4 mm in diameter, and are black or brown in appearance. With time, these spots can turn gray or white. If there are several spots on a leaf, the tissue between the spots can dry up and turn brown. Some varieties are more susceptible to Weather Fleck than others. Damage is typically greater if it is foggy or there is a rain or irrigation while ozone levels are high.

Leaf spots caused by ozone.

Post prepared and sent by Canadian Tobacco Research Foundation

Mailing Address: CTRF, P.O. Box 322, Tillsonburg, ON  N4G 4H5

Telephone: 519-842-8997

Web Address: http://ctrf1.com

Most crops are continuing to progress quite well. Cultivation is a common activity on most farms at this time. Side-dressing is also occurring now and will continue up until the last cultivation.

Stage of growth of an earlier planted field.

There are no widespread problems being reported at this time. Unfortunately, high winds earlier in the week did cause some damage to plants on some farms particularly on knolls and in the more open areas of fields.  Farm or field specific problems that have been reported since planting include fumigant injury, uneven plant stands caused by weaker plants, insect feeding from one or more of the following – cutworms, white grubs, seedcorn maggots and wireworms, salt injury to plants from fertilizer applied to close to plants, and planting of diseased greenhouse plants to the field. Plants infected by Bacterial Soft Rot and Black Root Rot have been seen in certain fields, which in these cases both diseases originated from infection in the greenhouse.

Black Root Rot is caused by the fungus Thielaviopsis basicola and can be found infecting greenhouse seedlings, particularly those grown in Styrofoam plug trays (see photos below). Planting infected seedlings in the field results in poor field growth and later maturity. Unless Styrofoam plug trays are properly sterilized following use each year, it is not uncommon for the fungus to build up in the trays.  Research at CTRF has found that a steam treatment of Styrofoam plug trays at 80°C (176°F) for 1 hour can provide good control of Black Root Rot contamination.  For more information on Black Root Rot and its control, please refer to the technical bulletin entitled “Tobacco Pests and Disorders in the Field – Black Root Rot” posted in the plant protection section under the research heading of this website.

Wilting of float tray seedlings caused by roots infected by Black Root Rot.

Roots in field infected by Black Root Rot that originated in the greenhouse.

Post prepared and sent by Canadian Tobacco Research Foundation

Mailing Address: CTRF, P.O. Box 322, Tillsonburg, ON  N4G 4H5

Telephone: 519-842-8997

Web Address: http://ctrf1.com

Planting of the crop is mostly complete with the majority of it having been done in May. Most fields were planted in a short time with good quality plants and, at this point, appear to be quite uniform.

An earlier planted field showing good uniformity.

To date, there have not been many problems reported. Some of the calls we have attended to regarding plant injury have been related to fumigant, fertilizer, and too high a concentration of an insecticide in the transplant water. Damage from cutworms and white grubs has also been reported, but there has not been anything too significant or widespread.

Plants in the row on the right are being affected by fertilizer that is too close to the roots of the plants. A rain or irrigation will lessen the high concentration of salts around the roots and help the plants to recover and establish.

Seedlings in most greenhouses continue to progress quite well. To date, very few problems have been reported.

Seedlings in a dry tray greenhouse on May 6, 2014.

Symptoms of cold injury to seedlings continue to be seen in both tray and muckbed greenhouses.

Now is the time that nitrogen deficiency can sometimes be seen in muckbed seedbeds, as was the case in a greenhouse we visited late last week. Nitrogen deficiency is often related to overwatering and/or mixing the muck layer with the sand underneath when preparing the greenhouse.

Nitrogen deficient seedlings are often observed to be in patches in muckbed greenhouses where the seedlings are slower growing or have almost stopped growing and are quite pale in colour.  Often the roots of these seedlings are white and very well developed even though the seedlings are still quite small. Application of nitrogen, preferably in the nitrate form, will be needed to get the seedlings growing again. Rates and application frequency are provided in OMAF & MRA Publication 842.

All growers should be on the lookout for cutworm feeding in their greenhouses. In a very short time, significant damage can be caused by these pests. Registered products recommended for control of cutworms in greenhouses can be found in OMAF & MRA Publication 843.

Fumigation started on a few farms earlier this week. The soil temperature measured at 15-20 cm (6-8 in) deep in a worked field that was prepared for fumigation was 11.5 ⁰C (53°F) in the mid-afternoon on Tuesday, May 6.  The air temperature at the time was close to 17⁰C. Judging from the current forecast, it is expected that the day-time air temperature will be similar or higher over the next 5 days.

Most growers seem satisfied with seed germination and seedling establishment in their greenhouses.  In some of the earlier seeded greenhouses an application of fungicide has been made for control of Rhizoctonia damping-off.  Clipping has started in some of the float tray greenhouses with more expected to start as the week progresses.

Last week signs of chilling injury were being seen in several greenhouses. The initial symptoms are often a bright yellow colour in the growing point of the seedling and upward cupping of the leaves. As the seedlings become larger and the leaves grow out (as shown below), some leaves will be malformed, cupped and have a distinct yellow/white discoloration. Chilling injury is caused by exposure of the seedlings to a large variation in air temperature, such as when ventilation occurs on a very cool but sunny day or at night when the temperature outside is quite cold and the temperature drops significantly in the greenhouse because the heaters do not have enough capacity to maintain the set temperature. Seedlings will outgrow chilling injury without any ill-effects.

Chilling injury

At this time of year, it is not uncommon to see the after-effects that algae can have on young seedlings in trays. Seedling stands can sometimes be reduced significantly if enough algae is present when the seedlings are in the 2-leaf stage. Affected seedlings turn completely brown after they are overcome by the algae (as shown below). Cool and cloudy conditions are ideal for algal growth in trays. Conditions that are optimum in the greenhouse for rapid seed germination and early seedling growth help seedlings to outpace the algae so that the seedlings become large enough that the algae can no longer affect them.  Not fertilizing for 2 or 3 weeks after seeding can also help to prevent an early buildup of algae in trays. Further information about algae can be found in the plant protection section of this website.

Seedling on the left (light brown in colour) has succumbed to the algae

A few growers have asked about using a low-phosphorus fertilizer in dry tray greenhouses, such as a 12-2-14, which is commonly used in float tray greenhouses. A low phosphorous fertilizer is not recommended for use in dry tray greenhouses because it has been observed to cause phosphorous deficiency.  This is when small, dark, circular shaped spots begin to appear on seedling leaves, which can look similar to the symptoms caused by target spot.  The affected leaves then start to yellow. A fertilizer analysis of 20-20-20, 15-16-17 or 10-15-20 has been shown to provide good results in dry tray greenhouses.

CTRF is pleased to announce the hiring of Dr. Catarina Saude as the Team Lead of CTRF’s Plant Protection Program. Dr. Saude worked as a Research Plant Pathologist for vegetable and horticultural crops in the Department of Plant Pathology, Michigan State University, and in the Department of Plant Agriculture, University of Guelph. Her work will focus on developing effective tobacco disease and pest control methods.  Dr. Saude is replacing Dr. Ron Brammall who is retiring.

This website contains some useful information on plug tray production of transplants. The three questions below are frequently asked by growers. The answers to these questions can be found in CTRF’s documentation on Plug Tray Seedling Production, available in the agronomy section of this website.

1. What fertilizer schedule should I use for dry tray production?

2. What are the optimum temperature conditions for seedling germination and early growth as well as plant uniformity?

3. What are the water quality guidelines for float tray production?

The annual tobacco variety meeting was held on February 20, 2014.  Highlights of this meeting are provided in the plant breeding area of the website.

With another greenhouse season soon to be here, things to be on the lookout for are provided in the plant protection area of the website.

In the plant breeding area of this website, results of an on-farm variety evaluation survey of CTH8 are posted.  CTH8 was grown on 6 farms in 2013 and the survey was completed by each grower.  The majority of growers, five of the six, indicated that they would grow CTH8 again.