Weather conditions have been favourable for ginseng growth over the past few weeks, and there are no reports of major disease or insect issues. However, the standard issues for this time of year are showing up. This includes Cylindrocarpon on isolated plants or patches of plants in older gardens, Phytophthora root rot in saturated areas of the garden, Alternaria within the canopy where fungicide coverage is difficult to achieve, and Pythium in some fields.

There are also issues with Rhizopus, which combined with another root disease like Cylindrocarpon can cause isolated roots to rapidly rot into a white, toothpaste like consistency. When the roots of these plants are dug up, they usually consist of a ball of mush with soil clung to the mass. The skin may remain intact. There is no evidence to suggest that the disease can spread through the soil to neighbouring roots very quickly, and the problem often remains isolated in the field. Little is known about this disease.

I have had questions recently about herbicide carryover from field crops to the ginseng crop, and which herbicides have the most potential for carryover. Pursuit (imazethapyr) residues can last at least three years in the soil and growers should avoid seeding ginseng after Pursuit for at least that amount of time. Other residual herbicides such as Callisto, Atrazine, Command and Prowl do not last as long as Pursuit in the soil, but may cause issues if ginseng is seeded the year after the herbicides are applied. To be safe, if ginseng is being seeded the year after corn or soybeans it is best to choose land where Round-up Ready or Liberty Link cultivars have been grown and residual herbicides would not have been used.

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