More than 40 visitors attended the day, which was led by ADAS consultants Andrew Hewson, Erika Wedgwood and John Buxton at Joseph Rochford Gardens, Hertfordshire. It followed two earlier events in Sussex and Herefordshire.
Hewson said the workshops were needed because "if the pesticide proposals being considered by the EU come to pass we will lose a lot of actives we currently use".
He added: "We have to learn to work without certain products and look at alternatives such as Compost Tea and SP Invigorator."
Hewson recommends a joined-up approach encompassing nursery hygiene, cultural and biological control of pests, weeds and diseases, regular crop monitoring, minimal use of compatible pesticides and the use of alternative products.
Entomologist John Buxton said it was exciting that a new biological control may have been found for carnation tortrix moth and apple moth. He has been working on an HDC project that has shown that Trichogramma wasps can parasitise the moths' egg masses, so that a wasp rather than a caterpillar emerges.
Trichogramma can be introduced on cards like Encarsia formosa, but Buxton plans to carry out a wider-scale trial to work out how the wasps can be most effective.
Ben Woolsey from equipment manufacturer and distributor Martin Lishman demonstrated the "redefined" Compost Tea unit, which is exclusively available in the UK and Ireland from the Lincolnshire-based company.
Hewson said the organic plant stimulant, which is created by brewing humic compost into a liquid containing living microorganisms, "bolsters against plant diseases".
"I know around 60 growers who are using it. They have found that they have been able to reduce fungicide use by around 75 per cent."
Abi Raiment of Dove Associates championed the use of soil improvers Caliente Mustard and BioFence. Caliente Brand Mustard is a green manure and biofumigates the soil by releasing compounds from Brassicaceous plant tissues which suppress soil-borne pests and pathogens. BioFence is a pelleted organic fertiliser also derived from a brassica crop. Both are available from Surrey-based Plant Solutions.