Developments for fruit growers

With some key chemicals set to go, new and overlooked products are coming to the fore, says Brian Lovelidge.

There are numerous new fungicides on the way that will control apple scab - photo: Brian Lovelidge
There are numerous new fungicides on the way that will control apple scab - photo: Brian Lovelidge

Although the proposed new EU pesticide regulations have caused consternation and turmoil in the crop production and protection industries, nobody yet knows for certain which products will go.

And when the chosen ones do go, it's not likely to be until 2014 at the earliest, leaving growers and their agronomists some time to find ways of adjusting to, or overcoming, the problems that the losses cause.

Meanwhile, numerous pesticides are in the development pipelines of those manufacturers with R&D programmes, such as BASF, Bayer CropScience and Syngenta, or will be launched within the next few years. Some of these products will help fill the gaps left by the implementation of the new legislation while many very good existing products based on modern chemistry appear to be safe.

Fruit growers will be able to derive comfort from knowing that their pesticide arsenal is or will be good enough to fill most of the gaps left by the losses. However, if the triazoles like Cultar (Syngenta), Folicur (Bayer), Indar (Landseer), Systhane (Landseer), Topas (Syngenta) and Weedazol (Nufarm UK) disappear, the skill and ingenuity of spray advisers and growers in keeping crops clean will be fully tested.

"We are working very hard to find alternative chemistry and have some really exciting products coming through," says Bayer CropScience communications manager Julian Little. "But it takes about £250,000 and 10 years to bring a new molecule to the market - and for every £10 in sales, we invest £1 in finding something better."

Over the next two or three years Bayer will introduce several fruit products if their Pesticides Safety Directorate registration is successful. The first one is spirotetramat, a unique new molecule, which, Little claims, is "extremely unusual" in being totally systemic. Its spectrum includes the normally difficult-to-control pests such as woolly aphid, mussel scale and pear sucker, and it is safe to beneficials.

Another of the company's imminent newcomers is a very strong mildewicide with some activity against scab, based on strobilurin and trifloxystrobin. Also on the way is a novel molecule that is very effective against scab, mildew and storage rots and, like the strobilurin product, should help fill any gaps left if Topas and Systhane are lost.

Popular improvements

A Bayer insecticide, Envidor, first available in 2008, is proving very popular among pear growers for sucker and rust mite control, and it also has good activity against mussel scale and spider mites. Hutchinsons' South East top fruit adviser, Graham Waters, used the product on virtually all of his growers' pears last year with very good results. The fact that it does not harm sucker predators, notably anthocorids, is an enormous advantage, he said.

Little is upset about the possible loss of Calypso, which - like the more recent introductions Certis's Gazelle and Syngenta's Centric - is a neonicotinoid. Although Calypso's main target is rosy apple aphid, it gives good incidental control of numerous other pests including rhynchites, scale insects and sawfly.

"Calypso is incredibly environmentally friendly and it even has the label possibility for spraying during blossom because it's so safe to bees," he claims. "It's really the future of crop protection rather than the past and it would be ridiculous to lose this sort of product."

BASF also has a number of fruit products in development although they are not far enough along to mention. It might be losing two of its biggest products, Stomp and Rovral, "but we won't let them go lightly", asserts the company's agronomy manager for specialist products Simon Townsend.

He says that its other major fruit products have been performing very well, both in the marketplace and agronomically. They include Bellis, which has good activity against Nectria canker, powdery mildew and scab. Its companion fungicide Signum has approval for blackspot, Botrytis and powdery mildew control on strawberries, and Botrytis and powdery mildew control on other berry fruits. The company also markets Maccani for controlling apple and pear scab, and powdery mildew on apples.

Townsend points out that these products can be used in programmes with Fargro's new biofungicide Serenade, based on a strain of Bacillus subtilis.

Fargro managing director Paul Sopp explains that although Serenade is registered for Botrytis control on protected strawberries it now has off-label approval for use on "virtually every other (fruit) crop you can think of".

Sopp adds: "The label recommendation only mentions Botrytis so the off-label approvals don't refer to anything beyond that, but in crops like apples its use will be for mildew and scab control. In Germany it's actually registered for scab control. It has a very broad spectrum for a fungicide as it has activity against most leaf and fruit diseases."

Sopp said that his company is looking at other biopesticides to follow on from Serenade. Like Serenade they will all be very useful for residue and resistance management purposes in conjunction with conventional pesticides whose useful life will be prolonged as a result, he points out.

Over the next four years or so the arsenal of fruit growers' will be further strengthened by a number of products that Syngenta plans to introduce. Those should more than compensate for its two triazoles, Topas and Cultar, which may be lost.

"We're not certain which triazoles will be affected or when," states Syngenta technical manager Pat Ryan.

Due to launch within the next 12 months is a combination fungicide containing fludioxinil and cyprodinil with broad-spectrum activity in top and soft fruit crops. It gives good control of powdery mildew and downy mildew, Ryan claims. The cyprodinil component will be launched as a separate product, probably in 2010, for powdery mildew and scab control on apples and pears.

A difenconazole product approved for brassicas should reach the marketplace in 2012 for controlling scab on apples. Another top fruit fungicide, coded 520, which may be produced in two or three forms and has a very broad spectrum, is expected to follow in 2012 or 2013.

Ryan said the company's acaricide Dynamec is expected to be registered for pear sucker, rust mite and fruit-tree red spider mite at the end of this year or early 2010. It already has off-label approvals as Acaramik for the control of two-spotted spider mite and leaf and bud mites on protected raspberries and blackberries, and tarsonemid mite on strawberry runner beds and protected strawberries.

Also, a product based on emamectin, from the same chemical group as Dynamec's active ingredient abamectin, should become available in 2011 for codling moth control in apples and pears.

United Agri Products senior fruit agronomist Colin Bird says that any recently approved products such as Steward (DuPont), Tracer (Landseer) and Runner (Bayer) - all for caterpillar control in apples and pears - are likely to survive the new EU legislation cuts. That also applies to the strobilurin products including BASF's Stroby, which has approval for powdery mildew control in apples, strawberries and blackcurrants, and apple scab.

However, he affirms that until the European Commission decides on the precise definition of an endocrine disruptor - one of the most important parameters being used to determine the fate of individual pesticides - nobody knows for certain which ones will have to go.

Triazoles, the mainstay of disease and weed control in apples, seem likely candidates. "If we did lose the triazoles, including the big three, Topas (Syngenta), Systhane (Landseer) and Indar (Landseer), it would leave us weakened but not fatally wounded," Bird says. "It would put more pressure on the alternatives for scab control like Scala (BASF), Dithianon (BASF), Switch (Syngenta), the strobilurins and others coming on stream.

"Folicur (Bayer), also a triazole, is important for post-harvest use, mainly against Nectria canker," added Bird. "But Cercobin got a SOLA last year for the same purpose. It was previously known as Mildothane but the trouble is that it selects resistant strains (of fungal pathogens) very quickly."

Identifying possible losses

Bird says that, although a triazole, Cultar (Syngenta) is not on the hit list. But if it did disappear there would still be Regalis (BASF) for growth control in apples and pears. Regalis is not suitable for all situations though. For example, in some years its maximum dose is not sufficient to do a good enough job and its 55-day harvest interval can be a disadvantage. On the other hand, Cultar can have adverse side-effects such as smaller fruit, shorter stalks and more russet on Cox but it has the advantage of long-term activity whereas Regalis does not.

The pyrethroids such as Talstar (Belchim) and Decis (Bayer) are also under threat, but they don't play a big role in fruit pest control, especially top fruit, according to Bird. However, there are good alternatives such as Gazelle (Certis) and Centric (Syngenta) for aphid control, and there is Masai (BASF) against aphids, fruit-tree red spider mite and two-spotted spider mite, and Sequel (Certis) for mite control.

Rovral (BASF) is another potential loss candidate, notes Bird. It's very important as a botryticide in soft fruit but is no longer - or rarely - used for drenching pears against Botrytis, although it still has approval for that purpose. This is because modern storage, better orchard hygiene and blossom sprays with Bellis minimise infection.

The dithiocarbamate fungicides Karamate (Landseer) and Triptam (Certis) might also be on the hit list. Bird said that if they go it would give growers less opportunity to ring the changes as an anti-resistance measure. Certis certainly would not be happy if Triptam went because it has only just introduced it, although the company's technical officer, Alan Horgan, believes that even if the worst happens it probably would not be for another five years or so.

Triptam is a useful fungicide because it is active against a range of fruit diseases including scab, Botrytis and cane spot. The same goes for Karamate as it can be used for foliar disease control in various currant crops and against scab on apples and pears.

Of the two herbicides that might go, Weedazol (Nufarm UK) - a non-selective, residual triazole product - would leave the biggest hole, asserts Bird. One of the first triazoles to be approved, it gives very persistent grass and broad-leaved weed control throughout the spring and summer, thus reducing the pressure on other herbicides such as glyphosate, which must be applied more often to achieve the same sort of result.

Stomp (BASF) is the other fruit herbicide that may be targeted, although this not certain as its maximum rate has been reduced from five to 3.3 litres/hectare. As a result, however, it's not so persistent, and the less susceptible weeds have become harder for it to control.


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