Rainfall has been highly variable in the ginseng growing area, with some areas getting very dry and others having experienced heavy rains from thunderstorms. Other than some heat stress issues from the heat earlier this month, the crop is progressing normally with no unusual issues reported.

Except for those fields that had flooding and high Phytophthora pressures, if you have high disease pressures at this time of year, you may need to consider one of two possibilities:

1. You are not getting good coverage of all plant surfaces. This is a good time to recalibrate your sprayers and/or replace nozzles. For a refresher on sprayer considerations for ginseng and proper sprayer setup and calibration, consult “How to Spray Ginseng” and “How to Set up a Crop Sprayer” on Sprayers101.
2. You may be dealing with resistance of the pathogen to one or more of the fungicides in your rotation. Resistance is the ability of a fungus to withstand a pesticide spray that was once able to control it. It builds up over time when a pest is repeatedly exposed to the same active ingredient or group, and individuals with mutations that allow them to survive a spray multiply and gradually (or sometimes rapidly) take over the population. See below for resistance management strategies.

Resistance Management Strategies

Resistance management may be more important for ginseng than any other crop. Growers manage three major foliar diseases, the causes of which are very prone to resistance due to their prolific production of spores and their ability to spread rapidly from field to field. These diseases must be controlled over a very long season from April to October, resulting in a high number of applications. Ginseng growers also have access to fewer new products than other crops given the relatively small acreage and less incentive for companies to register products.  Finally, ginseng has very low tolerance for any of these diseases because the plant cannot recover by growing new leaves over the season. Managing resistance has become even more critical because very few new products and modes of action are being introduced into the market for any crop.

While growers are generally familiar with the importance of rotating products for resistance management, there are some considerations to keep in mind to make the strategy more effective:

1. Consider resistance management for each disease separately. A product cannot help with resistance management if it does not control a disease. For example, if you apply a group 7 fungicide for Alternaria, it does not count for managing resistance of Phytophthora if the group 7 does not control Phytophthora.  
2. While some labels allow for consecutive sprays, it is best to never apply two consecutive sprays of chemicals in the same group. For example, if the first product applied contains a group 7 and 11 fungicide, avoid applying any product containing either a group 7 or group 11 fungicide for the next application, if possible.
3. Use your group M fungicides strategically. Products in group M have multisite modes of action that make it very difficult for a fungus to develop resistance. The main ones currently available for ginseng are chlorothalonil (e.g., Bravo, Echo), mancozeb (e.g., Manzate, Dithane), and captan (e.g., Maestro, Captan). It is best to mix these into the rotation to avoid applying too many single-site modes of action (e.g., groups 3, 7, 9, 11 etc.) in a row.
4. Use biofungicides (e.g., Minuet, Trichoderma products) and plant defence activators (e.g., Aliette, Phostrol) when possible. These types of products are also unlikely to develop resistance. They often provide disease suppression, rather than full control, but they are very useful tools in resistance management. Given their lower efficacy, they are best used at times with lower disease risk or in a rotation with highly effective products.
5. When applying two consecutive products in the same group cannot be avoided, rotating two different actives in the same group is better than applying the same product twice in a row (if it is permitted on the label). For example, while Lune Sensation and Merivon both contain group 7 and 11 active ingredients, it would be better to rotate between the two products than to apply one of them twice in a row.

Weed Control during Garden Preparation

During garden preparation, growers are often focused on erecting the shade structure and less focused on weed control in those new fields. It is essential to keep fields as weed-free as possible for the management of both nematodes and European chafer grubs.

Plant-parasitic nematodes such as the root lesion nematode and the Northern root knot nematode require the roots of a living host to develop and multiply. Both of these species of nematode have a very wide host range that includes numerous weed species. In a weedy field, anything that survives fumigation can begin to multiply before seeding. Once the straw is laid, they then transfer over to volunteer rye to multiply further before ginseng germination. Keeping the fields weed-free over the summer before seeding can reduce populations of both species, although it will not eliminate them.

European chafer adults lay eggs in open fields, such as those being prepared for ginseng seeding, in late June or early July. The grubs hatch 10-14 days later and then spend the next 11 months feeding on roots of grasses and some broadleaf plants. Once this generation of grubs pupate and emerge as adults, they leave the garden and do not return. They do all of there damage to ginseng in the spring of the seedling year.

While the grubs have the roots of volunteer rye to feed on after straw is laid at seeding, they should have nothing to feed on between early July and ginseng seeding. The only way the young grubs can survive between egg hatch in early July and the germination of volunteer rye in the field late in the summer is if the field is full of weeds during that period. It is also unlikely that the adults would lay eggs in a field if there were no plants in the field at that time (Figure 1).

Figure 1. A field being prepared for ginseng planting that was full of weeds at a time when adult European chafers were laying eggs. This makes the field much more attractive to egg laying, and allows young grubs to survive until ginseng seeding.

While cultivation is a very effective strategy for controlling weeds during field prep, herbicides may be needed to get weeds growing around the posts. Before seeding ginseng, any herbicide registered for control of weeds before planting of all crops can be used for this purpose.

The Value of Food Safety and Traceability Programs

Growers of many crops are required to adopt formal food safety and traceability programs (e.g., CanadaGAP) by their customers, such as grocery chains or other large buyers. Ginseng growers, while they may be following good practices, have not been required by their buyers to be certified by formal food safety programs. The main program available to ginseng growers is the Good Agricultural and Collection Practices (GACP) program offered by the Canadian Herb, Specialty Agriculture and Natural Health Product Coalition. There are numerous benefits of being formally trained and/or certified, including:

1. Major buyers, such as Natural Health Product Companies, may require it and will only buy from growers who are certified. You never know when the next opportunity for a sale may arise, and only those that are certified will be able to take advantage of it.
2. Protection of your farm and the entire industry if a food safety issue arises. Ginseng has a relatively low risk of transmitting foodborne illness, but any crop can be contaminated with things like heavy metals, metal or glass fragments, or other chemicals. If an issue occurs and it cannot be traced back to a specific source through a robust traceability program, the entire industry could face issues selling the crop.
3. Insurance companies often offer lower rates for product or service liability insurance for companies trained in formal programs. If you offer any value-added products and need insurance, following a GACP program could save you a lot of money.
4. Reduced liability for injuries to workers or visitors on the farm. Even if you follow good practices on the farm, if you cannot prove it through documentation, it does not count. A GACP program trains you to recognize hazards on the farm and put in place clear practices to mitigate the risk. If an injury to a worker occurs, your liability is greatly reduced if you can prove that training was provided and not followed.
5. Countries may enforce food safety programs on all importers at any time. The E.U., for example, has strict rules for importers of all agricultural and food products, and other countries could adopt similar rules in the future.
6. Being forced into good recordkeeping and managing risk can help a farm identify efficiencies that make it more economically sustainable.

Contact OGGA if you are interested in being trained in Good Agricultural and Collection Practices.