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Third area of chemistry neededIn view of these sudden resistance developments, companies and advisors realised that a third type of chemistry was required to be used alongside DMI and QoI fungicides to ensure effective control of Mycosphaerella. The chemical of choice is chlorothalonil, whose discovery dates back to 1964, a multi-site fungicide with which there have been no cases of resistance despite usage on some 150 crops and 300 diseases. Syngenta has access to chlorothalonil as a result of its acquisition of the ISK interests, including the Bravo brand and proprietary Weatherstik technology that ensures enhanced rainfastness. The need for chlorothalonil has already been recognised in Ireland where its usage jumped from 3,000 ha in 2002 to 96,000 hectares in 2003. UK approval for Amistar OptiSyngenta has acted quickly to get a registration for Amistar Opti, a formulation of azoxystrobin (100 g/l) with chlorothalonil (500 g/l) developed at Stein, and this has just been granted in the UK. The maximum use rate is 2 l/ha and 4 l/ha per crop, with the latest application timing GS51. Syngenta is recommending use at 1.25 l/ha or 1.5 l/ha for the best take-all effects of azoxystrobin. Amistar Opti will be slightly discounted compared with the price for the individual components, with typical grower prices at £17.50–19.50/ha. BASF and other companies are recommending chlorothalonil tank mixes with strobilurin and triazole products. European News and MarketsBASF REVEALS MORE ABOUT FLEXITYBASF has launched its new cereal fungicide metrafenone (BASF 560F) as Flexity for use in the UK this season, primarily for control of powdery mildew (Blumeria graminis) in cereals. It has been tested since 1997 across Europe and received its first European approval in the UK last year for use on wheat and barley (CPM October 2003). It also gives a useful reduction in eyespot infections by “collapsing” some of the mycelia, although this is not claimed on the UK label. Reliable robust performanceAccording to Ian Ford, technical services manager of BASF in the UK, Flexity gives “reliable robust performance, excellent safety and long residual activity”. BASF is not sure of the exact mode of action, but it acts at various key stages in the fungus life cycle. It inhibits mycelial growth on the leaf surface, the development of appresoria, leaf penetration, the formation of haustoria and sporulation. It gives protectant, curative and long residual control and exhibits no cross-resistance with existing mildew control products. Strobilurins, in contrast, mainly act on powdery mildew by preventing germination and have no curative action. Quinoxyfen acts primarily on appressorial germination and morpholine products have a curative effect by blocking sterol biosynthesis in the haustorium. One application per crop recommendedBASF is recommending one application per crop in combination with fenpropimorph and that it be used early for best effect, at T0 or T1 timing, GS30-32, to get the most out of its eyespot properties. The company suggests no more than two applications per crop and not in sequence. As mildew is an obligate parasite, low levels of visible symptoms do not mean that cereal plants are not under attack. There is increased leaf respiration and slowing of photosynthesis even before symptoms become apparent. Flexity gives good control up to 45 days after treatment and BASF claims that its activity is clearly above current market standards. Flexity is available in the UK now and is being sold as a 300 g/l SC formulation of metrafenone in one litre packs. The maximum dose approved is 1 litre/hectare and BASF is recommending application rates of 0.25-0.50 l/ha in a water volume of 200l/ha. There are no water course (LERAP) restrictions and product can be applied up to GS61. Approval for use in oats in the UK is anticipated in 2005. Specific cereal mildewicides are currently applied to about 600,000 hectares of cereals in the UK and BASF is expecting to take a sizeable chunk of this business with Flexity. Metrafenone was discovered by scientists at American Cyanamid, whose crop protection interests were acquired by BASF. Approval in other European markets is expected later this year and next year. The fungicide also shows considerable potential for use in vegetables and ornamental crops. Flexity is being formulated at BASF’s facilities in Tarragona, Spain. Positive start for Swing GoldBASF has reported positive results for the cereal fungicide Swing Gold (133g/l dimoxystrobin + 50 g/l epoxiconazole) in its initial season of sales in the UK, where the product received its first European approval (CPM June 2003). An application of 0.75 l/ha typically gave yield gains of 0.3 tonnes/ha at T3 timing, according to the company. BASF claims that it performed better than azoxystrobin and tebuconazole for about the same cost and has now become the T3 standard in the UK. According to BASF, Swing Gold gives the best Fusarium culmorum control at its full rate of 1.5 l/ha. BASF is currently working on specific variety recommendations for feed and milling as well as regional recommendations. UK PESTICIDE GUIDEThe 2004 editions of the UK Pesticide Guide and the e-UK Pesticide Guide have just been released by the joint publishers, BCPC and CABI Publishing. Both the book and CD-ROM include information on more than 1,400 pesticide products. There are over 130 new product entries and 13 new active substances, or mixtures of active substances, including six new chemicals which are listed for the first time. All products and active substances that lost their approval in 2003 as a result of the EU Pesticide Review have been deleted from the 2004 edition (www.ukpesticideguide.co.uk). On the CD-ROM product, LERAP classification, formulation type, chemical class, and off-label uses are available as searchable fields, along with approved crops and target pests. Off-label approvals are web-linked to the Pesticides Safety Directorate for access to the Notices of Approval. There are also embedded links to the Leatherhead Food International on-line database of maximum residue levels and to the UK Voluntary Initiative website where product Environment Information Sheets can be accessed. |