Soil fumigants and microorganisms

February 24, 2009

Categories: Basal Rot, Diseases and Pests, Fungus, Growing Daffodils, Nematode, Soil

Download PDF

1. The use of a cover crop, mustard or other, to fumigate soil is an interesting proposition. However, I would want to be sure that the treatment did not destroy or suppress beneficial organisms along with the bad guys. For example, there is a fair amount of research indicating that a naturally existing (in the soil) fungus, trichoderma ( a.k.a. gliocladium) virens, is a natural antagonist of fusarium oxysporum, the carrier of basal rot. Organisms like these are thought less likely to exist in subsoils like those used for “fill” in housing developments. Fortunately, the good guys can be purchased and added to the soil. I would not want to introduce a fumigant, either artificial or natural, which destroyed them. 2. There is some research, although not much, indicating that trichoderma harzianum may suppress or inhibit root and stem nematodes. 3. From what I can tell, the U.S. is far behind places like India in researching and commercializing the use of beneficial natural organisms in agriculture. Too bad they’re not into daffodils over there!

2 responses to “Soil fumigants and microorganisms”

  1. Keith Kridler says:

    Exactly right on this topic. More for use on a home garden where a person does not have room to rotate crops. Also commercially strawberries run into major problems after a year or two on the same grounds.
    I have an e-mail in for the plant pathologist to see if they actually have all of this documented and ready to share what they have found. He has mentioned these cover crops now for two years.
    Again he calls them soil fumigants so I assume it will nuke the top layer of soil. Probably everything including nematodes will repopulate pretty quickly from a foot or so below the decomposing materials. Keith Kridler

  2. Peter and Lesley Ramsay says:

    Hello All,
    Trichoderma has been in use in New Zealand for some time now. I understand that the pilot research in this area was done at Massey University and later was developed further in cooperation with the University of Washington at Seattle. Strawberry growers have experimented with it by inoculating it into the soil in the company of worms – the theory I guess is that the worms will spread this friendly fungus. Five years ago I had one of my daff patches treated. Unfortunately I did not have a control planting of the same variety of bulbs, but I can report that the growth and vigour of this patch was better than the other three patches planted at the same time. The bulbs lifted well with minimal losses to basal rot. Some noted rotters (eg Cryptic) lifted in excellent condition. I have not used trichoderma since but know that at least two NZ growers (Graeme Miller and Kevin Johnston) have used trichopels with some success. I also believe that John McLennan has tried Unite, a powder form of trichoderma, as a dip. He was kind enough to send me a jar of this substance last year but I regret to report that it is still stored in my fridge. I will try to remember to use it this year! If you read this John you might like to chime in.
    I have used trichopels with marked success on my roses. We get a lot of silver blight here thanks to our poplar trees. It is countered by drilling small holes in the crown of the plant and inserting trichopels. Bushes treated in this have remained free of the blight ever since.
    A properly constructed piece of research on the effects of trichoderma on daffs would be wonderful. Are there any prospective funders out there?