Top Crop Manager

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Leaf diseases fungicide update 2008

Here is a look at recent label changes and pending registrations.


April 8, 2008
By Bruce Barker

Topics

As Top Crop Manager’s Season Ready Issue goes to press, a number of pesticide companies had received new labels, registrations, and have some registrations awaiting review with possible registration in time for the 2008 spray season. Some of these pending registrations may have received registration while Top Crop Manager was at the printer, so check with local retailers for new registration updates. Here is a look at what has changed over the past year.

New Tilt half rate registration
Tilt fungicide from Syngenta Crop Protection Canada has beaen around for many years. Tilt, with the active ingredient propiconazole, has proven effective in controlling common leaf diseases such as tan spot, powdery mildew, rust and septoria complex in wheat, net blotch and scald in barley, and crown rust/septoria leaf blotch in oats.

Typically, Tilt is applied at 200mL/ac at the flag leaf stage of the cereal crop. Tilt is now registered at the 100mL/ac (half rate) applied to wheat and barley from Growth Stage 12 to 23 (two leaf and three tillers). The timing allows tank-mixing with registered herbicides such as Horizon in wheat.

Randy Retzlaff with Syngenta in Edmonton says the half rate provides excellent early season disease protection and consistent crop safety with all registered herbicides. “The practice is not designed to replace a full rate application of Tilt at the flag leaf, but to complement the producer’s options should disease be evident at the earlier stages of crop growth. It offers about a seven to 10 day suppression of diseases.”

Syngenta field trials showed that the half rate of Tilt provided a yield increase of six percent in wheat and eight percent in barley, compared to check.

Retzlaff offers these scenarios when Tilt half rate might be used:

  • When disease is evident at herbicide application, use half rate of Tilt and reassess disease pressure at flag leaf.
  • To help control early season disease pressure under tight cropping rotations.
  • To help maintain high quality and plumpness for all cereal varieties.
  • Wet conditions or irrigated fields where early season disease pressure is more likely to develop.

New Quilt fungicide (registration pending) for cereals
Syngenta has applied for registration of Quilt. Quilt has a combination of two active ingredients, propiconazole and azoxystrobin, and in trials has shown excellent control of a wide range of foliar diseases in wheat, barley and oats crops. The timing will be the flag
leaf stage (BBCH 37-39). Retzlaff says Quilt research trials have shown an increased level of disease control over other fungicides.

Quilt will have two rates, a low rate and a high rate. The high rate would be used for heavier disease pressure. “We’ve seen better disease control than other fungicides, giving up to three to four weeks of protection after application.”

Retzlaff says Tilt and Quilt will be complementary. Producers could use Tilt at the half rate early in the season, and then follow up with either full rate Tilt or Quilt at the flag leaf stage in order to obtain the best full season foliar disease control resulting in maximum crop yield and quality.

Headline Duo chickpea label update
In 2007, BASF launched Headline DUO, which contains Headline (pyraclostrobin; Group 11) and Boscalid (Group 7). Headline DUO is registered for control of all types of ascochyta blight in chickpeas. The registration was spurred on by the occurrence of ascochyta resistant biotypes showing up in western Canada.

Gerald Martens, biologist with BASF in Edmonton, Alberta, says that research has shown that the new strains of ascochyta in chickpeas were not controlled by strobilurin fungicides (such as Headline or Quadris) alone. He says that while the new strains may not be widespread, the strains pose a risk and require preventative resistance management practices, such as treatment with dual action fungicides.

As part of a disease and resistance management plan, BASF recommends Headline DUO be used in rotation with other fungicide products with different modes of action, or multiple modes of action, such as Bravo. Martens says a typical application would be Headline DUO as a first application at the seven to 10 node stage of chickpeas, followed by Bravo fungicide 10 to 14 days later, with a third Headline DUO application seven to 10 days after the second
application. A fourth application of Bravo could be made if disease pressure warrants. Sequential or back-to-back applications of Headline DUO are not recommended, and no more than two Headline DUO applications per year are registered.

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Proline fungicide widely available for 2008
Proline fungicide from Bayer CropScience is a systemic fungicide that offers broad spectrum disease protection in several key crops. Proline provides enhanced control of sclerotinia in canola compared to current market leading canola fungicides. It also provides suppression of fusarium head blight in barley and wheat, control of net blotch, scald and spot blotch in barley, and control of glume blotch, speckled leaf blotch, tan spot and leaf rust in wheat. In chickpeas and lentils, Proline provides control of ascochyta blight, while also providing a new mode of action in the pulse fungicide category to help limit the development of fungicide resistance.

Proline is a new Group 3 fungicide in the triazole chemistries, containing the active ingredient prothioconazole. As a systemic fungicide, it provides curative, protective and eradicative activities. As a new Group 3 fungicide, Proline can offer another option for rotating
fungicide groups.

Bayer CropScience vice-president, industry relations and market development, Paul Thiel says that Proline brings a new level of sclerotinia control to canola growers, and research trials showed that sclerotinia control was better, and canola yields were higher when Proline was used, compared to other registered products.

Leaf disease rate for Folicur
Bayer CropScience is also promoting a leaf disease rate for Folicur again in 2008. That rate is three-quarters of the standard fusarium head blight (FHB) rate of 40 acres per 4.73 litre jug (118mL/ac.). Folicur has been used primarily for FHB suppression, but also offers control of key leaf diseases in wheat such as rust. At the three-quarter rate, Folicur provides better efficacy on leaf rust than other leaf disease fungicides in wheat.

The three-quarter rate of Folicur is 53 acres per 4.73 litre jug (88.5mL/ac). It is registered for use on leaf diseases in wheat. For FHB suppression, the standard rate of 40 acres  per jug is recommended.

Stratego tank-mix with herbicides
Thiel also says that the use of Stratego in herbicide tank-mixes in both wheat and barley increased in 2007. According to Thiel, applying Stratego in a herbicide tank-mix protects young wheat and barley crops from early season leaf disease. Stratego offers two active ingredients, propiconazole and trifloxystrobin, which provide two different methods by which the product prevents and eradicates disease in the plants.

Scott Henry, fungicide research and development manager with Bayer CropScience, says that Stratego showed significant efficacy on crown rust in oats in 2007. In Henry’s research trials, Stratego provided a 41 percent yield increase over the untreated oats because of rust control. Stratego is not labeled for a herbicide tank-mix in oats, but is labeled for leaf disease control outside of a herbicide tank-mix.

Protects Oats
There is an amended registration for use of the fungicide Headline in oats for the control of crown rust (Puccinia coronata), says BASF Canada. Crown rust is identified in the form of uredinia on both the upper and lower surfaces of the leaf. Uredinia is a reddish, pustule-like structure that is formed on the tissue of a plant infected by a rust fungus and produces uredospores. Damage to leaves, particularly the flag leaf, reduce photosynthesis and interferes with transport of photosynthesized sugars from leaves to the developing grain. The disease develops best during mild to warm (20 to 25 degrees C) sunny days and mild nights (15 to 20 degrees C) with adequate moisture for dew formation. Moderate to severe epidemics can reduce grain yield by 10 to 40 percent.

To maximize yield in cereals, it is important to protect the flag leaf from disease. For optimal disease control, Headline should be applied immediately after flag leaf emergence, says the company. The recommended use rate is 120 to 160 millitres per acre (0.3 to 0.4 litres of product per hectare). A second application can be made 10 to 14 days later if the disease persists or conditions are favourable for disease development. -end-