March 2011. An interesting article (below) was seen on the Wageningen UR website concerning biological control of nematodes in greenhouses. None of the methods was outstanding, but incorporating fresh organic matter yielded the "best predicable result".
Other methods tried were:
- biofumigation using cabbage leaves
- Pasteuria penetrans
- Baijens cultivation system (for cucumber) - two rows of cucmber are planted in one row and separated above soil level, allowing treatments on the larger row spaces (e.g., nematode controlling plants, or biological soil fumigation during cultivation.
Members suggested other techniques:
- planting tomatoes as a trap crop, so their growing roots will attract the juvenile nematodes, and when cysts begin to form on the roots, pull them out.
- Verticillium chlamydosporium cultured on compost as an alternative to the commercially available spore-preparations. The challenge is in finding a suitable isolate that will both grow on ordinary compost (much like mushrooms farmed on straw) as well as retain its effectiveness as a nematophagous fungus. The complexity increases by 'rotation' with crops which suppress nematodes.
- It was also noted the benzyl isothiocyanate is derived from Carica papaya seeds.
A member also gave information on the use of mustard oil by horticultuists in Queensland, Australia. It is a soil conditioner that acts as a soil fumigant. It can be seen as an effective and presumably much safer than methyl bromide, etc. It can be applied through a drip irrigation system or watered in by hand for small areas.
As with the other brassciae the active agent is methyl isothiocynate. It certainly takes care of pathogenic nematodes and the soil fungi that beset crops grown under protection. It also kills snails and slugs that shelter under plastic mulches. It has killed mole crickets and dollar spot on a putting green.
The seed cake from which the oil has been removed is really a waste product, but it is a good organic fertilizer. The member mixed it with potting soil for Strelitzia seedlings. They stay in their pots for 2 years and - in my nursery at least - weeds are a problem. The pelleted cake gave them a really good growth start and kept the weeds away - at least for a couple of months.
Another member mentioned that Schering Agro GmBh (before they were bought out) used to market methyl isothiocyanate as Ditrapex or Vorlex and it was freely available from the mid-1960s. Supply has now been discontinued. It was particularly useful for apple replant disease and was very effective against all nematodes including Meloidogyne javanica - its only drawbacks were that it was as poisonous as EDB (oral LD50 489 mg/kg), very corrosive and had to be soil injected. It was also twice the price of EDB being used at the same rate. Unlike Methyl Bromide, weed control was not one of its strengths.