Little is known of the ability of mint strains of the fungus to reproduce or to cause disease on other crops and weeds. But it is thought that populations of this pathogen can be maintained at low levels by superficial infections root infections on many plant species. These infections may not have obvious symptoms.

Native spearmint is relatively resistant, but Scotch spearmint is quite susceptible. Grasses including corn and related crops do not sustain the population, but fallow or grass rotations alone may take many years to effectively reduce soil populations below economic levels.

1. Use certified Verticillium-free stock for new plantings.
2. If possible, plant in fields that have not had a history of growing mint. Rotate infested fields with corn and alfalfa.
3. Take severely infested areas of a field out of mint production to prevent spread to new areas or fields. Do not plant mint there for 6 to 10 years unless soil is fumigated before planting.
4. Remove badly infested fields from mint production before wilt becomes so severe that mint will no longer grow.
5. Begin a program of field flaming when wilt first appears in a planting. Fields severely infested with wilt will not respond to flaming.
   
   1. Western Oregon -- if possible, flame within 1 week after harvest to allow regrowth before frost. This will strengthen the rootstock. If necessary, irrigate after harvest to keep soil moisture adequate for growth. Flame at 1.75 to 2 mph with 40 psi gas pressure.
   2. Central Oregon and Malheur County, OR -- Flame in fall in fields after wilt has appeared, and cultivate only when necessary to control soil insects and soil compaction and for stand regeneration.
6. Plant 'Todd's Mitcham', 'Redefined Murray', 'Roberts Mitcham' or other improved cultivars which have some resistance to Verticillium wilt and may be cropped successfully on lightly infested soils. In addition to the above cultural controls, observe the following guidelines in using these cultivars.
   
   1. Never immediately replant these cultivars in a field where peppermint has failed due to Verticillium wilt.
   2. On heavily infested soil, rotate out of mint at least 5 years before planting unless soil fumigation precedes planting; otherwise the new planting is likely to fail. Even 5 years may not be sufficient if growing something other than cereals or grass seed.

Consider the field's history in deciding whether to use fumigants and, if so, at what rate. Wilt potential, or the probability of disease, is related directly to the amount of wilt in the last peppermint crop and the number of years since the last peppermint crop that the field has been in crops other than mint.

Verticillium wilt potential is high in fields where peppermint has failed due to Verticillium wilt and the fields have been rotated to other crops 4 years or less. Wilt potential is low in fields that had a small amount of wilt in peppermint, in fields never in peppermint but that have received Verticillium inoculum from windblown dust, water, , etc., and in fields moderately to lightly infested but rotated out of mint 5 years or more to crops other than cereals or grass seed.

1. Telone II at 19 to 22 gal/A for a low-wilt-potential field, at 32 to 44 gal/A for a high-wilt-potential field. Maximum rate is 55 gal/A. 5-day reentry. Restricted-use pesticide.
2. Telone C-17 at 25 gal/A for a low-wilt-potential field, at 27.5 gal/A for a high-wilt-potential field. 5-day reentry. Restricted-use pesticide.
3. Vapam HL at 37 gal/A for a low-wilt-potential field, at 75 gal/A for a high-wilt-potential field. Also to prevent spread within a field. Note Low rate may not adequately control nematodes. 48-hr reentry and/or while tarps are being removed.