The Pest Management Regulatory Agency (PMRA) has phased-out the use of the active ingredient diazinon as of December 31, 2016.  As a result, Diazinon 50 WSP can no longer be used in tobacco greenhouses to control Pavement Ants.  Any leftover product should be disposed of in an environmentally responsible way, such as through the CleanFARMS obsolete pesticide & livestock medication collection program.

Over the past 2 years, the Canadian Tobacco Research Foundation (CTRF) has conducted research trials to find a replacement for Diazinon 50 WSP.  Several products were found to be efficacious in controlling Pavement Ants in tobacco muckbed greenhouses.  Data from this work is currently being considered by the registrants of these products for supporting a submission for minor use registration.

In the interim, there are currently no pest control products registered and recommended for control of Pavement Ants in tobacco muckbed greenhouses.  In past research studies, Pavement Ants were observed to prefer cornmeal to tobacco seed.  Near the walkway, you can place bait stations, which are made up of cornmeal placed in a covered container with holes placed on the sides near the bottom of the container.  This may entice the Pavement Ants to feed on the cornmeal rather than the tobacco seed in the seedbed.

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

Telephone: 519-842-8997

Web Address: http://ctrf1.com

Presidio^® Fungicide has been granted registration for control of Blue Mold on field tobacco.  It is a liquid suspension concentrate that contains 39.5% of the active ingredient (a.i.) fluopicolide.  Presidio^® Fungicide is the sole component of the chemistry group 43 fungicide that has both systemic and translaminar action and works on contact.  It is effective against several oomycetes including Peronospora tabacina, the pathogen that causes Blue Mold on tobacco.

Presidio^® Fungicide has both preventive and curative activity and it works by interrupting the pathogen’s cell structure.  It must be applied on the plant foliage prior to disease onset in tobacco or at first indication that Blue Mold is in the area.  A second foliar application may be made with a minimum treatment interval of 7 days between applications.  The application rate is 292 mL/ha.

For resistant management, Presidio^® Fungicide should be applied in a tank mix with a labelled rate of another fungicide registered and recommended for Blue Mold control, but with a different mode of action.  Currently the options are Aliette WDG or Quadris Flowable.  A maximum of two foliar applications of Presidio^® Fungicide (584 mL/ha) per season is permitted.  When applying Presidio^® Fungicide, use sufficient water to guarantee good leaf coverage.  A minimum of 200 L of water/ha is recommended.

The re-entry interval (REI) after application is 12 hours and the pre-harvest interval (PHI) is 7 days.

The Canadian Tobacco Research Foundation (CTRF) evaluated Presidio^® Fungicide in several field experiments and found the fungicide to have no effect on tobacco yield and quality.  The Tobacco Review and Evaluation Committee (TREC) also found the fungicide to be acceptable for use on flue-cured tobacco.

Even though Blue Mold on field tobacco has not occurred in Canada since 2008, it is important that products be available for control in the event the disease reappears.

Always read the label before applying a pest control product.

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

Telephone: 519-842-8997

Web Address: http://ctrf1.com

Agronomic performance data for the registered varieties grown in 2016 can now be viewed in the plant breeding area of the website.

Registered and promising varieties on display at the Open House on December 21, 2016.

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

Telephone: 519-842-8997

Web Address: http://ctrf1.com

CTRF is holding an “Open House” on Wednesday, December 21 between the hours of 8:30 a.m. and 12:00 noon.  Cured leaf samples of registered and promising varieties will be on display.  Handouts on the performance of the registered varieties will be available.  There will also be a plant pathology display in CTRF’s research lab.  Click here for the program and directions.

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

Telephone: 519-842-8997

Web Address: http://ctrf1.com

With harvesting completed earlier in October, CTRF will now begin to evaluate the tobacco cured from several of the field trials conducted in 2016.

Variety trials being harvested for the final time near Delhi, ON on October 5, 2016.

Similar to last year, a total of 42 promising flue-cured varieties were tested in replicated trials, with some of these varieties being grown at multiple sites.  The main objectives of CTRF’s breeding program are to develop varieties with good quality, high yield and disease resistance.  Several varieties under test have resistance to Black Root Rot, Tobacco Mosaic Virus, and/or Potato Virus Y.  Screening of breeding lines with high tolerance to Root-Lesion Nematodes is also occurring.  CTRF will again be holding an Open House later this year for growers to view cured leaves from the registered varieties and the new varieties that show the most promise for registration.  Agronomic data of these varieties will also be made available at the Open House.

In the plant protection area this year, several field trials were undertaken involving the control of Aphids, Root-Lesion Nematodes, White Mould, Blue Mold, and Pavement Ants (in the greenhouse).  New crop protection agents were evaluated as controls for these insect pests and diseases.  In some cases, the disease was not present in the field in 2016, such as Blue Mold.  Even though the disease did not occur, the effect of a new crop protection agent on leaf yield and quality can still be determined.  Data collected from all of the field trials will be analyzed once the yield and grade assessment of the cured tobacco has been completed.

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

Telephone: 519-842-8997

Web Address: http://ctrf1.com

An extended period of hot and dry conditions, which slowed the maturity of most crops, appears now to be over. With more seasonal weather conditions anticipated, the rate at which the remainder of the crop matures should improve.  It is expected that most growers will need the rest of September and into October to complete harvest.

No widespread disease or insect problems in the field have been reported to date this harvest season. Also, there have been no reports of Blue Mold in Ontario grown tobacco in 2016.

As a result of the dry season so far, nitrogen availability to the crop has been ample and suckers have been more of an issue this year than most.  In some fields, stalks are crooked from high winds experienced during a storm earlier in the season, which has made it difficult to properly apply contact sucker controls.

A long yellowing period when curing has been quite common on several farms this season. Fortunately, there have not been many complaints about curing diseases, such as bacterial soft rot and pole rot, which can become more severe when the yellowing period is long.

Earlier this season, we observed plants in several fields that were infected with Tobacco Streak Virus (TSV) (see photo below). No significant economic losses occurred in these fields because of the virus.  Sometimes this virus is mistakenly referred to as Tobacco Etch Virus, since some of the symptoms are similar.  TSV has been reported here in Ontario in tobacco since the 1930’s, but has never caused significant losses.  One unique trait of TSV is that the plant will recover from the viral infection.  Usually, 3-6 leaves about mid-plant will show infection from the virus, while leaves at the top and bottom of the plant appear normal.  More detailed information about TSV can be found in the Plant Protection area of this website.

Leaves showing symptoms of Tobacco Streak Virus – white lesions present on leaves and along veins, and browning of lesions on older leaves.

At this time of year, CTRF’s field research trials are also being harvested.  In addition, monitoring of these trials is ongoing.  Below is a photo showing tip leaves being measured in a fungicide evaluation trial near Aylmer, Ontario.

Tip leaf measurements in research trial.

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

Telephone: 519-842-8997

Web Address: http://ctrf1.com

To date, hand harvesting has begun on several farms, while machine harvesting is just getting underway. Irrigation is still a common site on many farms.  While the hot and dry conditions continue to persist, this moisture is needed to help develop the top of the plant now that most crops have been topped.

Tobacco being irrigated following topping.

To date, there have been no significant disease issues reported. Observed at very low incidence has been Sore Shin, Black Root Rot, Target Spot, White Mould, Potato Virus Y (PVY), and Bacterial Soft Rot.  No Blue Mold has been observed in any fields in Ontario so far this season.

Pressure from Green Peach Aphids is typical for this time of year. Hornworm populations have been on the low side in most fields for most of the season.  Japanese Beetles no longer appear to be a threat in most fields.

Unlike the past couple of years, damage from weather fleck that is caused by air pollutants has been minimal so far.

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

Telephone: 519-842-8997

Web Address: http://ctrf1.com

Calls have come in regarding leaves wilting in the top of the plant. The question often is whether the wilting is being caused by stink bugs or something else.  Figure 1 shows leaf wilting that is caused by feeding from stink bugs.  Often feeding damage from a stink bug can be seen on the upper leaves or stalk of the plant.  Another cause of leaf wilting in the top of the plant can be from high temperatures (i.e. in the 30s (°C)) and moisture stress, which have been common conditions this growing season.  Figure 2 shows a leaf that has wilted at about the 4th to 5th larger leaf down from the bud.  No signs of stink bugs or feeding were evident and, as a matter of fact, several plants in the field were showing the exact same symptom.  This type of leaf wilting was caused from high temperatures and moisture stress.  Leaves that become severely wilted in the top of the plant will often not recover properly and will remain small and be deformed.  Figure 3 shows an area of a field that is near a cedar hedge.  The damage from excessive heat and moisture stress is much more distinguishable and significant on several of the upper leaves since airflow in these types of areas is very minimal.

Figure 1. Tobacco plant showing symptoms of feeding from stink bugs.  Leaves in growing point are wilted.  Stink bug can be seen on the plant’s stalk just below the lowest wilted leaf. (Click on image to enlarge.)

Figure 2. Leaf wilting in upper portion of plant caused by high temperatures and moisture stress.  Because of the damage, some of these leaves may not recover properly and can remain small and be deformed.  Photo taken July 15, 2016.  (Click on image to enlarge.)

Figure 3.  Upper leaves of plants damaged by excessive heat and moisture stress adjacent to a cedar windbreak where there is minimal airflow.  Photo taken July 15, 2016.  (Click on image to enlarge.)

Aphids and hornworms (see Figures 4 and 5) are being seen in fields now. Please refer to an earlier post in crop news on this website for information on thresholds and treating for these pests.  Additional information about aphids and hornworms and their control can be found in technical bulletins posted in the Plant Protection area of this website and in OMAFRA publications 842 and 843.

Figure 4. Red morph of green peach aphids on backside of leaf in bud of plant.  Photo taken July 18, 2016.  (Click on image to enlarge.)

Figure 5. Tomato hornworm feeding on a plant.  Photo taken July 15, 2016.  (Click on image to enlarge.)

Japanese beetles are also being seen in some fields.  These beetles have shiny, coppery coloured wings and a metallic green head (see Figure 6).  Feeding by Japanese beetles can result in holes in leaves, but the more distinguishable feeding by them is when only the veins of the leaves are left without any tissue between them or in other words the leaf becomes “skeletonized” (see Figure 7).  There is no threshold established for Japanese beetles in tobacco here in Ontario, since damage is typically not significant enough to cause economic losses and warrant treatment.

Figure 6.  Japanese beetle on tobacco leaf. (Click on image to enlarge.)

Figure 7. Feeding from Japanese beetles is starting to “skeletonize” the end of the tobacco leaf. (Click on image to enlarge.)

Late in June, we had our first report of tobacco infected with Potato Virus Y (PVY) (see Figure 8).  It is not known as to how significant PVY will become this year.  Spread of PVY is primarily by aphids.  Control of aphids in tobacco may help to reduce spread of the disease from infected plants within a tobacco field.  For more 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 area of this website.

Figure 8. Tobacco plant showing symptoms of the necrotic strain of Potato Virus Y (PVY). (Click on image to enlarge.)

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

Telephone: 519-842-8997

Web Address: http://ctrf1.com

Blue Mold on tobacco continues to move in a northerly direction in the United States.  Areas most recently reporting the disease include southern Virginia, Lancaster County in Pennsylvania and eastern Tennessee.  Earlier in the season there were reports from North Carolina, Georgia and Florida.

To date, there have been no reports of Blue Mold in Ontario.  Growers should routinely scout fields for signs of Blue Mold (see photos below for some of the symptoms).  More detailed information about identification of Blue Mold and its control can be found in the technical bulletin entitled “Tobacco Pests and Disorders in the Field – Blue Mold” posted in the Plant Protection area of this website and in OMAFRA publications 842 and 843.  If you find Blue Mold, please report it immediately.

Yellow lesions on the upper surface of leaves at the bottom of the plant are an early symptom of Blue Mold.

Bluish-grey spores on the underside of the leaf are another symptom of Blue Mold.

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

Telephone: 519-842-8997

Web Address: http://ctrf1.com

Cutworms, aphids and hornworms are insect pests that can attack tobacco plants after transplanting.  High population density of these insects can cause significant losses.  Thus, the need for field scouting to ensure that these insects are kept under damaging levels, or below economic thresholds.  This is when the population density at which the costs associated with pest management may be offset by the value of potential yield loss associated with the pest feeding or damage.

Scouting for cutworms, aphids and hornworms requires adequate selection of field sites for a good estimate of each insect’s distribution in the field.  Plants selected for observation should be pre-selected at random before starting scouting to avoid biasing counts by selectively stopping at damaged plants.  The number of sites selected in a field depends on its size.  The more selected and checked sites, the higher the scouting accuracy.  For instance, for fields 2-4 ha (5-10 acres) in size, 5-10 randomly selected sites throughout the field are required.  For fields larger than 4 ha (10 acres) the number of sites checked is increased by 1 site for every hectare (2.5 acres).

Scouting for Cutworms

Cutworms are post-transplant soil insects that damage tobacco during the first four to five weeks after transplanting.  The darksided cutworm is the most commonly seen cutworm on tobacco.  It can damage a tobacco plant by creating holes in leaves, feeding extensively on the growing point (heart) or cutting off the stem at the soil surface.  Studies indicate that a low to moderate population level of cutworms can result in 20-40% damaged plants and a 14-25% loss of yield.

Damage to a tobacco transplant from cutworm feeding

Scout fields for cutworms weekly, from transplanting through to early July.  Cutworms are most active at night; therefore, evenings and early mornings are the best time to scout for these insects.  Select and stop at 5-10 sites or more and examine 20 plants per site for signs of cutworm feeding (holes in leaves, missing growing points, or stems severed at soil line).  Treat the field when at least 5% of the plants show signs of cutworm feeding, or when 2 or more cutworms are found per 100 plants.

Information about cutworms and their control can be found in the technical bulletin entitled “Tobacco Pests and Disorders in the Field – Insect Pests: Cutworms, Wireworms and Seedcorn Maggots” posted in the Plant Protection area of this website and in OMAFRA publications 842 and 843.

Scouting for Aphids

Aphids, mostly the green peach aphids are often seen on tobacco anywhere from about four weeks after transplanting through to topping.  Aphids can be black, orange or green in colour and winged or wingless.  Adults and nymphs damage tobacco by piercing the leaves and drawing large quantities of plant sap.  Studies indicate that a heavy infestation of aphids reduce the price of cured tobacco leaves 5-50% and also have an effect on chemical constituents of the leaves and yield.  Aphids are also vectors (carriers) of important tobacco viruses such as Potato Virus Y (PVY), Cucumber Mosaic Virus (CMV); Tobacco Etch Virus (TEV) and Tobacco Vein Mottling Virus (TVMV).

Wingless aphids – adult and nymphs; and, aphids feeding on upper leaves of tobacco

Scout fields for aphids from June through to topping.  Stop at 10 or more sites per field and examine 20 plants per site.  Check for aphid adults and nymphs on the underside of the upper tobacco leaves.  Early in the season, special attention should be given to areas near the field edges, since most aphids migrating from other crops land in these areas of tobacco fields.  Treat the field when 10% of the plants have 50 or more aphids on the upper leaves.  An exception would be when aphids are detected in tobacco fields near potato, tomato and pepper fields.  These fields should be treated as soon as possible to reduce the possible risk of a virus spreading in the tobacco from the neighbouring crops, particularly PVY.

Information about identification of aphids and their control can be found in the technical bulletin entitled “Tobacco Pests and Disorders in the Field – Insect Pests: Aphids” posted in the Plant Protection area of this website and in OMAFRA publications 842 and 843.

Scouting for Hornworms

Hornworms, mostly the tomato and tobacco hornworms, are caterpillars that attack tobacco plants about five to six weeks after transplanting.  The two species of hornworms are biologically similar and are distinguished mainly by the number and shape of the white stripes on each side of their bodies and the colour of the horn on their back end.  The tobacco hornworm has seven diagonal white stripes with black margins and its horn is usually red. The tomato hornworm has eight V-shaped stripes with green margins and a bluish black horn.  Hornworms are voracious feeders.  Young hornworms feeding on tobacco cause small holes in the leaves, while mature hornworms can strip the top and mid leaves of plants leaving only the midribs and main leaf vein.  Studies on hornworm damage and crop loss, indicate that 100 hornworms feeding on tobacco leaves can result in 2 kg (72 oz) cured leaf loss, which is an average of 20.4 g (0.72 oz) of cured leaf per hornworm.

Tomato hornworm and leaf damage caused by a hornworm

Scout fields for hornworms from July to August.  Because of their green colour and preference for the underside of the leaf, hornworms are difficult to find until the damage has occurred.  The presence of distinctively barrel-shaped insect droppings, a sign of hornworm infestation, can help locate the insects in the field.  Stop at 5-10 sites per field and check the underside of leaves of 20 plants at each site, and record the number of hornworms.  Treat when the population averages 1 or more hornworms per 20 plants.  Often, hornworms are parasitized by other insects such as the Cotesia wasp.  Parasitized hornworms should not be included in the scouting counts.

Hornworm parasitized by Cotesia wasps

Information about identification of hornworms and their control can be found in the technical bulletin entitled “Tobacco Pests and Disorders in the Field – Insect Pests: Hornworms” posted in the Plant Protection area of this website and in OMAFRA publications 842 and 843.

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

Telephone: 519-842-8997

Web Address: http://ctrf1.com