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Processing Crop Update: Tomato & Pepper Edition Prepared by Janice LeBoeuf, Vegetable Crop Specialist Questions? Comments? Season Summary 2004 The Processing Crop Updates are prepared through the season. Would you like to be added to the e-mail distribution list? Call me at (519) 674-1699 or email janice.leboeuf@omaf.gov.on.ca 2004 Processing Crop Update Topics - Tomtoes and Peppers
2004 Processing Crop Update Topics - Tomatoes and Peppers
Read the latest Processing Crop Updates ("Tomato and Pepper" or "Sweet Corn, Beans, and Pea" editions) at http://apps.omafra.gov.on.ca/scripts/english/crops/agriphone/index.asp. A sampling of 2004 articles from the Tomato and Pepper Processing Crop Update is below. | Top of Page |
Effects of Cool Temperatures on Tomato Plants Often, our early-planted tomatoes have to endure some cool weather. Here’s a bit of a review of the effects of low temperatures on tomato transplants. Tomatoes stop growing, and are susceptible to chilling injury, at temperatures between 0 and 10° C (32-50° F). Chilling injury can show up after short periods of the lower temperatures or long periods of the higher temperatures and can cause stunted growth; wilting, surface pitting or necrosis of foliage; and even increased susceptibility to disease. Low soil temperatures also stunt plant growth and prevent root development. In addition, plants that are not actively growing would be expected to have a tougher time metabolizing herbicides. Cool soil temperatures mean that phosphorus is mostly unavailable, while lack of root growth limits the plant's access to soil nutrients. The combination of all these factors can result in some poor looking plants, but the crop should recover when warm temperatures return. Plants that have been severely stressed, however, may be slow to resume growth and may have lost some yield potential. Not all cool-temperature effects show up right away. Low temperatures experienced by the plant 4-5 weeks (!!) before flower buds are visible, can affect flowering and fruit set. In tomato, freezing damage occurs at -1 to -2° C (28-30° F). It may be difficult, initially, to determine whether the growing point has been killed and damage may become more evident on the day after the frost. Besides cool temperatures, young, early-planted transplants may also experience wind whipping, wind desiccation, and possibly sandblasting. Strategies to combat this include:
using wind protection systems (cereal crop wind strips, cover crops, crop residue) | Top of Page |
Tomato Bacterial Disease Control Strategy For tomato transplant production, a registered fixed copper fungicide should be applied according to label instructions, starting 2 ½ weeks after seeding, then every 5 days for a total of 5 applications. Apply in sufficient water to wet foliage just to runoff, not to drench the plug. This should be applied after the last watering of the day. For the field grower, ensure that your transplants have received the recommended copper spray program in the greenhouse. In the field, start to apply a registered copper fungicide within 7 days after transplanting - apply at least 3 applications at 7-day intervals. Continue applications if conditions are very favourable for bacterial disease. Applications can be discontinued at first fruit set. Many research trials across North America have shown that tank-mixing mancozeb with copper enhances bacterial disease control. Note: Most bacterial speck populations in Ontario are resistant to copper fungicides. Always read and follow label directions. | Top of Page |
Resistance Management: A Who’s Who of Tomato Fungicides With all these new fungicides available, it is getting hard to keep track of what is what. Here’s a summary of the fungicide groups and disease spectrums of the tomato fungicides. Remember, to avoid the development of disease resistance, rotate between fungicide groups.
* The M group is multi-site contact activity fungicides. There is no cross-resistance between subgroups of the M group. This group has a low risk of resistance development. Notes on new fungicides: Cabrio EG (pyraclostrobin)
Quadris FL (azoxystrobin)
Tanos 50 DF (famoxadone/cymoxanil)
Lance WDG (boscalid)
TomCast DSV maps are now online at http://www.ownweb.ca/lib/tomcastdsv.cfm. As of June 14, DSV accumulations since May 15 ranged from 16 in east Kent to 39 in the Lighthouse Cove area. To review the program, tomato fields that were planted before May 25 should have their first fungicide application when 35 DSVs have accumulated from the planting date. Fields planted after May 25 can wait for 45 DSVs to accumulate before their first fungicide spray. If the DSV threshold (35 or 45) is not reached by July 11 (July 18 for extremely late plantings), make the first fungicide application at that point anyway. Subsequent fungicide applications should be made when 20 to 25 DSVs (18-20 DSVs for mancozeb) have accumulated since the previous spray date. You can use the longer spray intervals when you have applied the strobilurin fungicides (Cabrio EG, Quadris Flowable). Remember to alternate strobilurin applications with other fungicide families. Lance (boscalid) and Tanos (famoxadone/cymoxanil) are new registrations for 2004. Use the shorter spray intervals with these products, until we learn more. When using mancozeb, do not extend the respray interval beyond 20 DSVs. Growers who have previously applied copper/fungicide combinations for bacterial disease control can restart their DSV accumulations as of the last spray date IF they used a FULL RATE of fungicide at that time. In areas not covered by the TomCast system, start fungicide applications when first fruits appear and re-spray at 7 day intervals during continuous warm, moist (dews, fogs, or rain) weather or at up to 12-14 day intervals in warm, dry weather if diseases are under control. Be sure to read the label before applying any fungicide. This is even more critical when you have not used the product before. | Top of Page |
There are a number of fixed copper formulations registered for disease control in field tomatoes, field peppers, and/or greenhouse transplant production. According to research by Dr. Ron Pitblado at Ridgetown College, there is not a great deal of difference in efficacy between formulations. Instead, your choice of product may be based upon ease of use, price, or availability. Here is a summary of some of the commonly available fixed copper formulations that are registered for disease control in tomatoes and peppers - and their labelled uses.
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We all know the damage that the variegated cutworm can cause. This pest can be difficult to control if not noticed early, so be sure to scout your fields frequently (at least once per week) and thoroughly. Dig down into the canopy to look for signs of the worm. Scouting in the early morning or evening (or on cool, overcast days) will improve your chances of finding the worm – necessary to find out what range of sizes you have – but if disease is present in the field, it is best to scout when the foliage is dry. Although the presence of adults can be detected using pheromone or black light traps, this will only indicate when intensive field monitoring should begin, as trap catches do not predict the level of worm infestation. Generally, scouting should begin by mid-July. Insecticide treatments can effectively control the larvae, but must be applied when the larvae are very young. Older, larger larvae may not be controlled. Evening applications of insecticide can improve control. Adjust water volumes depending on the size of the plants, to ensure penetration into the lower canopy. Good spray coverage is essential. Water sensitive paper placed at several points in the crop canopy can show whether the spray solution is reaching its target. Check the latest edition of OMAF Publication 363, Vegetable Production Recommendations, for chemical control recommendations for variegated cutworm and other worm pests. Once the re-entry period has passed, it is very important to scout the fields again to determine the effectiveness of the treatment. Rotate insecticide families to avoid development of resistance. Always read and follow label directions. | Top of Page |
Season Summaries and Back Issues on OMAF Web-site Back issues of the Processing Crop Update: Tomato and Pepper Edition or Sweet Corn, Bean, and Pea Edition are available on the OMAF Web-site. Go to the main OMAF Vegetable page at http://www.omafra.gov.on.ca/english/crops/hort/vegetable.html, click on "Newsletters and Crop Updates", then "Processing Crop Updates". You will find them under "Vegetable Updates" on this page. The December 31, 2003 and December 2, 2002 Updates are Season Summaries, and each includes a handy chart of the contents of each issue from that year. This makes it much easier to find a particular article or topic. | Top of Page | |
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