Article taken from Agronomist and Arable Farmer magazine
Fruit growers packed out a recent meeting in Kent to catch the latest news and technology updates!
Spotted wing drosophila (SWD) is now an established and important pest of stone and soft fruit in the UK, Agrovista's recent fruit seminar at Brands Hatch in Kent, was told. The fly can cause serious dam-age in fruits, particularly late-ripening cherries, Agrovista fruit agronomist Alex Radu told the meeting. ""SWD can also be a big problem in plums, and soft fruit is affected;' he added. Season-long monitoring was vital, Mr Radu advised.
""I recommend deploying Dross Traps from the end of February in woodlands, where the pest overwinters. Then use monitoring traps in the crop from March onwards and consider perimeter trapping to delay entry to crops.""
Fruitlet and fruit monitoring, using sugar flotation tests and looking for physical fruit damage, was vital, he added. Cultural control measures, such as fine nets to slow pest ingress and clearing alternative hosts such as brambles and wild damsons, had met with some success. Crop hygiene, including disposal of waste fruit and removal and treatment of SWD-infested fruit (e.g. enclosed composting, processing or freezing), was also key. Growers had a restricted choice of crop protection products and targeted applications were required to achieve good control. Alternating products was vital to avoid build-up of resistance, he said. In cherries, Tracer offered very good adult control — seven days of robust protection — but had some impact on beneficials. Hallmark also delivered good adult control but was damaging to beneficials. Exirel controlled adults and offered very good reduction of egg-lay, he added. Pyrethrum SEC, Spruzit and Gazelle gave limited adult control, though Spruzit also offered limited egg control. The first two products were damaging to beneficials, while Gazelle was safe. Mr Radu's product list for plums was almost the same, except Exirel, which was not approved in that crop, was replaced by Decis.
New cherry varieties to help maximise output
Cherry growers planting new orchards should consider trialling new varieties before committing to a potential 20-year investment. Several newcomers could help growers increase yield and maximise the percentage of Class 1 fruit, said Leon Jihad, technical consultant to Agrovista's top fruit agronomy team. ""We have very good quality, mid-season varieties, but we need to search for excellent early and late varieties.""
Good storage potential, higher yields and orchards that were earlier coming into high production were key attributes. Late varieties showing promise included Czech variety Tamara, Mr Jihad’s favourite, which had a long picking window. Its big shoulders could retain water and increase risk of splits, but the variety out yielded Kordia and had a good shelf life. Areca was easier to get into production than Cordial, he said. Fertard, a very late cherry, could make a good alternative to Sweetheart, as the fruit was firm and did not split so easily. Another candidate was Astrid, a smaller cherry with excel-lent eating quality that appeared easy to get into production. New early/mid-season varieties included Poisdel, an early cherry (week 2-3) with good shelf life. Folfer was a very good, firm cherry but needed covering. New varieties from independent German breeder Peter Stoppel looked exciting, he added. The programme focused on very early or late varieties selected for out-door production in a very high rainfall area (1,200mm/yr). ""These are superb conditions for scab and splitting — a very good environment for selecting cherries," said Mr Jahae. B062 was a very early fruiter with 100% split tolerance, and F091, another early, produced very firm, extra-sweet fruit which was also split resistant. Of the late varieties, 6111 looked promising, a good storing variety picking five to seven days after Staccatto. ""This could extend the season to early October," said Mr Jahae.
New fungicide formulation offers enhanced activity
Apple and pear growers will have access to a new formulation of scab fungicide dithianon this season. Delan Pro from BASF contains 125g/litre of dithianon and 561g/1 of potassium phosphonates (phosphite), known as KHP, a new fungicidal active for top fruit in the UK. Rate is 2.51/ha up to six times per season. Simon Townsend, BASF agronomy manager for fruit and vegetables, said dithianon provided preventative multi-site activity while KHP stimulated the production of defensive compounds to help protect plants from disease (known as systemic acquired resistance). In 19 out of 21 trials Delan Pro had been more effective against scab than dithianon (as Dithianon WG) applied at the old label rate, despite delivering just 313g of the active/ha compared with 525g. ""I would bet my salary on it being at least as robust;' said Mr Townsend. Delan Pro was not yet cleared for use on cider apples or perry pears, he added. BASF's IPM programme to control codling and tortrix moth using a combination of mating behaviour disruptor pheromones (RAK 3+4) and a nematode-containing biopesticide (Nemasys C) was showing great promise in trials, said Mr Townsend. The 1PM programme hits the pest at two stages. Nemasys C is applied to bark during diapause in September/October, when larvae rest before pupating. RAK 3+4 dispensers, which last for nine months, are hung in orchards before first flights (in April), flooding the area with female pheromones so males cannot locate partners. Work with Agrovista in Cambridgeshire last year in a high-risk orchard backed up earlier work which showed the system could eliminate moth mating and egg laying. Untreated areas showed high levels of codling moth activity in June, resulting in 60-70 codling-affected apples per 1000 fruit. In RAK-treated areas only one or two fruits were affected per 1,000. ""Even under high pressure this system operated very effectively;' said Mr Townsend.”RAK 3+4 is approved in Belgium;' he added. ""We are waiting for re registration then aiming for approval by mutual recognition in the UK.""
Boosting earwig populations
Developing earwig-friendly spray programmes could help apple and pear growers control damaging pests, the audience heard. Earwigs were important predators of aphids, particularly woolly apple aphids, as well as of codling moth eggs and larvae, said Dr Michelle Fountain of East Malling Research. ""However, there are large variations in earwig populations, and they are low or absent in many orchards."" Data from lab and field work showed that chlorpyrifos was highly toxic to earwigs, causing 100% mortality within a few days of spraying. Spinosad had a lesser, delayed effect, though mortality still rose to 50% after 85 days in the lab. Abamectin showed some long-term mortality, as did spirodiclofen and thiacloprid, the latter being the more harmful. Flonicamid harmed earwig nymphs, while methoxyfenozide slowed their growth. Indoxacarb was harmful to males. ""We need to look after earwigs in apple and pear orchards," said Dr Fountain. ""We need to assess populations to identify where they are healthy and where we need to encourage numbers to increase.”We need to avoid using harmful pesticides at key times of year. This includes the spring, when nesting females are foraging, and from May through to October to protect young earwigs and adults. ""Occasional applications of acetamiprid/thiacloprid for early season pests are unlikely to have long-term effects if earwig populations are high, but we need to consider cumulative effects of insecticides on earwig populations.""
Beneficial fungi raises yields and quality
Inoculating fruit trees and sterile soft fruit substrate such as coir with mycorrhizal fungi could increase plant growth yields and quality, according to Dr Louisa Boyer of Kent-based manufacturer Plant Works. Mycorrhiza formed a symbiotic relationship with plant roots, and could increase active uptake of mineral nutrients and water by 700 times, she explained. ""Mycorrhiza are very important for phosphorous and nitrogen uptake, and help protect plants from, stresses, such as pathogens and drought, and can help heavy metal tolerance."" However, mycorrhiza may be seriously depleted in some soils. Ploughing, the use of some systemic fungicides and intensive nutrient programmes could all affect populations, Dr Boyer explained. And it was absent from sterile substrates such as coir. EMR work showed inoculation was beneficial to strawberry plant growth, producing an average 10-20% increase in class 1 fruit in coir substrate, using commercial fertigation. In addition, 40% less irrigation could be used while still retaining the crop, said Dr Boyer.