Crop Update

Even though ginseng plants are starting to show signs of senescence, especially in frost damaged gardens, it is still important to monitor the crop closely and ensure the crop is protected from disease. This includes foliar diseases that don’t often cause direct damage to the root such as Alternaria and Botrytis. There can still be significant increases in root weight in September if the tissue remains healthy. Botrytis is continuing to cause patchy damage in ginseng gardens. While Alternaria levels have been relatively low, spotty damage cannot be ruled out.  

Due to the repeated rains and prolonged period of disease pressure, protective sprays have been repeatedly applied over a long period. In years like this it is especially important to prevent the development of resistance in the fungi by continually rotating registered products. Why is this necessary? Due to the vast number of individuals in the fungal population, there are always a few that develop resistance to some products, meaning that they begin to tolerate the chemical being applied and are no longer killed by it. If the same product is applied over and over, these resistant individuals survive and continue to multiply while the susceptible ones are killed. Eventually the resistant ones dominate the population and the product becomes completely ineffective. By rotating products with different modes of action, individuals that are resistant to one product will likely be killed by another, and the population remains susceptible to each of the products. 

Some Notes about Ginseng Seed

Seed Size

Ginseng seed mostly falls within 4 commercial seed sizes: Size 11-12 (small), Size 12-13 (medium), Size 13-14 (large), and Size 14-15 (extra large). These seed sizes vary in their performance in the field. Embryo lengths vary greatly between the sizes. Percent final emergence is highest for medium and large seed and lower for small and extra large seed. Small seed can also produce a root that is up to 30% smaller by the end of the first year due mostly to smaller leaves. Sizing seed, especially removing the small seeds, can improve stand in the field, reduce variability, and increase average root weight.

Stratification

Most ginseng seed today is stratified above ground. Successful above ground stratification depends on proper temperature and moisture levels. De-pulped green seed should be mixed with sand in a 1 part seed to 2-3 parts sand ratio. Hold seeds at 3^oC. Fluctuations in temperature will result in delayed germination. Do not add water to seed boxes. Allow seeds and sand to dry out and keep relative humidity as low as possible.

Viability

Germination tests are not practical for ginseng seeds because of the long stratification period. However, it is possible to do a viability test. The test of choice is called a tetrazolium test. It can be used for dormant seed such as ginseng, but it will not tell you if there will be delayed germination. It needs to be done by a professional to interpret the results correctly.

Dry Seed

When seed is allowed to dry out in the stratification bins it will be reduced to about 12% moisture. At one time, seed drying was thought to be something to avoid. However, dry seed is not dead seed. It does not need to be re-hydrated before seeding, although it will not hurt to do so. Dry seed can be planted directly into seed beds. It will re-hydrate naturally over the winter months and the embryo will develop and reach germination size by the spring. You need to make sure of a good mulch layer. If the seed freezes before it re-hydrates, it will not survive.

Seeding Rates

When it comes to seeding rate, more is not necessarily better. Optimal seeding rates are not the same for every field and every situation. In some cases, such as under low seed and root prices, it may make sense to increase seeding rate, because any increase in yield will increase returns. Under high seed prices, a lower seeding rate would make more sense. Also, the risk of root disease increases as seeding rate increases. That is because disease can spread more easily from root to root when they are closely spaced. If you are planting into land that is sub-optimal for ginseng, a lower seeding rate may help reduce disease pressure. Roots under high plant stand may also be more spindly than under low plant stand. A moderate planting density of 80-120 lbs/ac is often ideal. 

Banking Seed

It is possible to bank ginseng seed for more than one year. Not all of the ginseng seed will survive, but survival rates can be reasonable if it is done properly. To do this, the seed must have been allowed to dry out during stratification. To keep it beyond one year, the seed must be kept dry and cold (1-3^oC) without fluctuation in temperature and at low relative humidity. It is unknown how long seed can be banked successfully. The risk of disease increases the longer it is stored. 

Questions about ginseng can be directed to Sean Westerveld, OMAFRA’s Ginseng and Medicinal Herbs Specialist at 519-426-4323; E-mail: sean.westerveld@ontario.ca.