Production of Puccinia thlaspeos 'woad' strain inoculum using traditional farming equipment

Puccinia thlaspeos 'woad' strain is a systemic rust used for biological control of Isatis tinctoria (Dyer's woad) and registered with the Environmental Protection Agency under the name Woad Warrior. It is an obligate parasite and inoculum can only be produced on living plants. Isatis tinctoria was planted in March 2001 and inoculated by spraying with Puccinia thlaspeos teliospores on 17 May and 1 June 2001. Symptoms were apparent on some plants on 20 October 2001 but 83% showed systemic infections by 3 April 2002. The rust-infected plants were harvested 24 May by cutting with a Milholland 1495 swather with crimping to condition plants for rapid drying. Plants were left in the windrow to dry until 28 May and baled using a Heston 4950 inline baler. Bales of infected woad were ground on 30 May using a Gehl chopper with a 1/16-inch screen. The number of basidiospores produced from farmed inoculum was 80% of the number of basidiospores produced from hand-harvested leaves from rust-infected wild woad plants. Traditional farming methods and equipment can be used to produce large quantities of Puccinia thlaspeos 'woad' strain inoculum.