Last year at the IOBC conference on greenhouse IPM in the UK, we were talking with Dr Richard GreatRex, field development manager with the UK biocontrol company Syngenta Bioline, about visiting a large greenhouse vegetable producer with a successful IPM history and he suggested Hedon Salads in Yorkshire. This interested us as Marilyn had previous history with the company going back almost 25 years and we were keen to learn of their progress in that time.
Back in 1989, Marilyn visited what was then called Carrdale Growers near Hull, the forerunner of Hedon Salads, with IPM researcher Rob Jacobson, based at Horticultural Research International near York in the north of England. She met Tom Salmon, a young UK greenhouse producer. Later that year Tom accompanied Rob to Canada to have a look at the work Marilyn was doing with Don Elliott, founder of Applied Bionomics on Vancouver Island, BC, in the development of biocontrol programs in the greenhouse vegetable industry in Alberta. They were particularly interested in the development of one of the first successful IPM programs for WFT, using the relatively untried predatory mite Neoseiulus (Amblyseius) cucumeris.
In 1993, Tom Salmon co-founded Hedon Salads. A visit by Stephen was organised by Linda Aitken, IPM adviser with Syngenta Bioline, which is the contracted IPM provider to Hedon Salads. At the Newport site, Lyndon Speck, general manager, with 20 years’ experience with Hedon Salads, four of these at the Newport site, talked about the company and its IPM, which he seemed pretty happy with.
In 2012, Hedon Salads is one of the largest fresh produce companies in the UK, presently employing over 180 staff. The Hedon Salads Group owns two production sites outside of Hull in the East Riding of Yorkshire and it has been joined by a sister company NE Growers nearby at Selby. Newport is the principal site and head office. Hedon Salads is the largest UK producer of aubergines and overall has 24ha (60acres) under glass. This article focuses on the 2011 IPM program at Newport.
Horticultural practices at Hedon Salads appeared to be fairly standard. They have a Combined Heating and Power Plant or Co-Generation as it is known in Australia that creates electricity from gas-engine driven generators. Heat and CO2 wastes are used in the glasshouse. Excess power goes to the national grid. Crop planting starts in week 1 each year and crops are removed in November. Crop plants are grown in Grodan blocks with three plants per 1m Grodan slab. Peppers (capsicums) are grown at 7.2 heads/m2 and aubergines (eggplant) at 5.8 heads/m2. Both have 3 stems/plant. The 12-year-old Newport glasshouse and also its location in the north present a productivity challenge. Yields are lower in the north of England than in the south due to lower light levels and the old glass doesn’t help. Presently, long sweet-pointed peppers produce 17.5kg/m2, bell peppers (all colours) 26kg/m2 and aubergines 42kg/m2. At Newport, they employ 30 full-time staff, 10 summer casuals and 4 apprentices. Peppers are marketed through Sainsburys, while aubergines are marketed through Tescos, Sainsburys and ASDA. At the end of the crop, a mat is rolled down the pathway between a pair of rows, the crop is cut and thrown onto the mat, a machine then winds the mat out onto the concrete roadway down the centre of the glasshouse and the plant material is passed through a shredder. Shreddings are thrown out onto nearby fields for composting. This is a very good way to deal with waste crop material, which otherwise could be a source of future pest and disease problems. In Table 1 crop areas for 2011 and in the current 2012 season are shown. It demonstrates their changing priorities, with Hedon Salads venturing into strawberries at Burstwick and NE Growers.
Hedon Salads IPM
Syngenta Bioline has been dealing with Hedon Salads for over 19 years. In that time they have worked in partnership to develop effective IPM programs to control pests in their crops using the minimum amount of pesticides. But as with other successes in this area, a good IPM consultant has been guiding their hand. Syngenta Bioline’s Linda Aitken is there each year, starting with a suggested annual release strategy agreed to prior to crop planting. The actual program, as might be expected, depends entirely on the way the season unfolds, but the tools and strategies are in place beforehand.
You will note some similarities in the IPM programs between the hydroponic strawberry operation featured in our last article (PH&G Issue 123, March/April 2012) and here. I think we sagely noted that while “no two IPM programs (are) alike, success has a formula.” Have a good consultant, start with clean growing conditions, monitor for pest activity and have an integratable biocontrol release and chemical use plan. At Newport it starts with good hygiene practices between crops. The 6.4ha of glasshouse structure is washed down with standard horticultural disinfectant and water. Floor polythene may be changed though sometimes this is used for two seasons and grow bags (slabs) are replaced with fresh ones. There are alcohol hand-gel and disinfectant foot baths at the entrances to their glasshouse. All staff crop-walk weekly and report their findings. Sticky traps are used early in the season, but are not continued with once the crop gets to head height.
In 2011 they grew sweet peppers and aubergines in what was a relatively quiet year IPM-wise with no one pest causing unexpected problems and no disease problems in either crop. Biocontrol agents (BCAs) supplied by Syngenta Bioline and supporting chemicals used in the Hedon Salad IPM programs are shown in Table 2.
Aubergine IPM program 2011
Linda explained, “Aubergines are a crop that has often been avoided by growers in the UK because of its potential pest problems. Hedon Salads has proved that with attention to detail and the correct biological and chemical inputs a quality crop can be grown successfully. In the early days of IPM at Hedon Salads, crops were attacked by whitefly and thrips in particular, but an IPM program was developed and adapted over the seasons to a point where these pests are rarely a problem now. Early identification of pest species and swift curative action as well as robust preventive inputs of beneficials, have all led to this achievement.”
As a preventive measure against whitefly, Encarsia formosa was introduced at 3/m2 weekly from planting and all the way through to about a month before the crop was pulled out. Macrolophus pygmeus (formerly M. caliginosus) was introduced in February, although it also feeds on many other pests. Transeius (Amblyseius) montdorensis introduced for thrips control is also useful against whitefly. Sticky traps are placed above the crop from the start and any hint of whitefly results in more traps and higher rates of E. formosa plus areas targeted with sprays of SB Plant InvigoratorTM (SBPI), SavonaTM (insecticidal soap) and EradicoatTM/MajestikTM (similar starch-based insecticidal products) applied twice a week until control is achieved. Fortunately, whitefly didn’t appear in the 2011 crop. Linda stressed the importance of keeping whitefly out of the crop rather than having to deal with an established population.
Linda said, “(Presently), aphids are the worst pest of aubergines. It is important to monitor and to have species identified to ensure the correct BCAs are used.” Three parasitoids and one predator are the mainstay. Aphidius colemani is used for small aphids such as green peach aphid, Myzus persicae. It is used preventively at 0.25/m2/week from week 1, increasing to 1/m2/week when aphids are seen. Aphidius ervi and Aphelinus abdominalis are used against larger aphids such as foxglove aphid, Aulacorthum solani, and potato aphid, Macrosiphum euphorbiae. Aphelinus gives best results against A. solani. The predatory midge Aphidoletes aphidimyza can be introduced at 0.5/m2/2-3 weeks into hot spots as they favour colonies rather than individual aphids. In this crop, aphids, first seen in week 7, were already parasitised by A. colemani indicating the strategy was working. Control continued with BCAs and spot sprays of SBPI were applied until week 13 when pymetrozine was used to halt spread. Pymetrozine is a useful integrator with most BCAs, although it can harm Macrolophus.
Spider mite was first seen in week 13. Phytoseiulus persimilis was introduced weekly to known infested areas and as occasional blanket treatments at 4/m2 afterwards. By week 29, spider mite was difficult to find and what remained was being fed on by Macrolophus and naturally occurring populations of the predatory midge Feltiella acarisuga. A clean-up spray with spiromesifen was applied in early September. SBPI, Savona and Eradicoat or Majestik can also be used against spider mite hot spots. Neoseiulus (Amblyseius) californicus, a predatory mite, can be usefully released in hot, dry areas.
Thrips were managed preventively with Neoseiulus (Amblyseius) cucumeris at 1 controlled release sachet (CRS)/plant at commencement of flowering. This can be repeated after 6 weeks if pest levels are high. This gives early protection from thrips. Small surges in thrips numbers can be reacted to by extra introductions of more N. cucumeris or T. montdorensis can also be used. Macrolophus can also assist in controlling thrips. Orius laevigatus has not been found to be effective in aubergines and isn’t used at Hedon Salads. Following onion thrips, Thrips tabaci, damage seen on leaves in week 19, N. cucumeris and T. montdorensis sachets were introduced to known infested areas and damage was halted by week 22, which is an excellent result.
The bumblebee Bombus terrestris was used for pollination. In previous years bumblebees used early in the season were replaced with honeybees from April as they were cheaper. However, honeybees were not available this year.
Macrolophus was released in aubergines for whitefly control in previous years, but this pest has not been seen in this crop recently. Macrolophus has proved particularly versatile, also feeding on thrips, spider mite, leaf miner, leafhopper and aphids. While not completely controlling them, it does provide additional help. However, it will also feed on beneficials such as Aphidoletes and Feltiella larvae, although this effect has never been catastrophic. Leafhopper does not have a specific BCA, but can be controlled by Macrolophus.
Pepper IPM program 2011
Lyndon said: “Disease is a minor issue. Downy mildew previously recorded one year was successfully treated with azoxystrobin. Macrolophus is not often used on peppers, because it doesn’t establish very well on the smooth leaves.”
Aphid is also the worst pest in this crop. Green peach aphid first seen in week 9 was already parasitised by A. Colemani, which had been released at 0.25/m2/week preventively after planting. Releases were later increased to 1/m2/week. Aphids were controlled using BCAs and SBPI until week 17 when pymetrozine was used to halt spread. Another pymetrozine application was used in week 25 to knock back aphids and this also reduced capsid (mirid) damage in the crop.
Thrips were only occasionally seen on sticky traps in this crop. They can be a problem, as can tomato spotted wilt virus, but not this year. Neoseiulus cucumeris was released preventively against thrips at 1 CRS/5 plants at commencement of flowering, while Orius was released at 1/m2 in mid-February. In bad thrips years, N. cucumeris release can be repeated at 6 weeks or T. montdorensis can replace N. cucumeris or be used in addition to it and Orius repeated twice more totalling 3/m2. Hot spots are countered with extra CRSs of predatory mites and Orius. This program works well.
Spider mite seen from week 11 was targeted with a minimum P. persimilis releases into hot spots and spot sprays of SBPI. Regular blanket releases with P. persimilis at 4/m2 follow as required. Excellent control was achieved by week 22 and by week 29 it was difficult to find live spider mites. As mentioned for aubergines, natural Feltiella was also present and contributed to spider mite control. Mini sachets of Amblyseius andersoni were used as a preventive measure in susceptible areas 2-4 weeks before spider mite was normally expected. Neoseiulus californicus was used in hot, dry areas as in aubergines.
Caterpillars of turkey moth, Chrysodeixis chalcites, and tomato moth, Lacanobia olerace, caused some damage from week 27. These were spot sprayed with Bacillus thuringiensis and cleaned up with indoxacarb in week 29, which also cleaned up the growing population of leafhopper at the same time. Hedon Salads doesn’t use Trichogramma egg parasitoid as they haven’t had much success with them and similarly with pheromones for these species. However, Orius introduced for thrips will feed on caterpillar eggs.
Leafhopper is becoming an important pest and good weed control in the immediate surrounds to the glasshouse is recommended. Sticky traps hung low will catch adults.
Some pesticides were used in these programs, but generally, supermarkets guide producers on the chemicals that they can use on their fresh produce and of course they must be selective for BCAs to be used in IPM. Chemicals advised by Syngenta Bioline for Hedon Salads to use in support of BCAs are shown in Table 2. They are similar for both crops. Spinosad is available against thrips, although resistance makes it less useful, while spiromesifen for spider mite can interfere with egg-laying in P. persimilis and other phytoseiid predatory mites if used mid-season and is perhaps better used as an end-of-crop clean-up. A number of physically acting products such as the insecticidal soap product Savona, the starch-based products Eradicoat and Majestik and the natural product SBPI, are all quite useful and fairly popular in UK IPM programs. We are keen on these biorational or reduced-risk types of products and researched the efficacy of a number of them against key greenhouse vegetable pests in our latter years with NSW DPI.
Encouragement for IPM in Australia
Producers in the UK have grown up with IPM and are familiar with its practices and in having the help of biocontrol companies at their back door. Australian producers are less familiar with IPM even though much has been written and said about it over here. Experienced advisers are thin on the ground and Australia is a large country. Cost is often raised, but this is a red herring for as anyone would know, the cost of a crop protection program is a small percentage of the overall crop production cost. At Hedon Salads, Lyndon estimated their IPM cost for pests to be about £5000/ha in a good year, such as occurred in 2011, and up to double that in a bad year, with labour occupying about 30% of this cost. But he sleeps well knowing he doesn’t have chemical failure to worry about. The pesticides he uses are there to back up the BCAs.
Some growers are worried that they might be taking a risk with IPM. Not so. As we have shown here, Hedon Salads has a robust fully integrated biological and chemical IPM program. Looking closely at the chemicals they use, you will see that they are used strategically and sparingly, but still used when needed. Success with IPM in aubergines and peppers at Hedon Salads followed years of development and advisory support. Lyndon said: “It was worth the perseverance.”
About the authors
Stephen Goodwin and Marilyn Steiner are IPM consultants trading as Biocontrol Solutions at Mangrove Mountain. Email: email@example.com
The authors would like to thank Linda Aitken, Syngenta Bioline and Lyndon Speck, Hedon Salads, for providing information for the article.
PH&G May/June 2012 – Issue 124