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Foliar Phytophthora Alert Foliar Phytophthora has been found in some areas. Damage is mainly found on the upper parts of the stem and on the leaves (Figure 1). Sporangia of the fungus were found on affected tissues and contained well developed zoospores. Spores produced on ginseng leaves will be airborne and can spread large distances by wind. Windy conditions occurred during and after the rainfall on Thursday. This could have resulted in widespread dissemination of spores throughout all ginseng growing areas. With more wet weather expected on the weekend, it is important to protect the crop from foliar Phytophthora in all ginseng gardens immediately. Aliette is the only fungicide currently registered for use on foliar Phytophthora. Control of the root rot phase of the disease is important for reducing foliar infections. Ensure timely application of Ridomil Gold and Aliette throughout the season. Consult the labels for application rates and procedures Sporadic frost damage has also been reported in some areas. This can easily be confused with Phytophthora since damage occurs in low areas of the garden where Phytophthora root rot is often concentrated. Damage due to frost typically affects the entire stem and leaves and often can result in twisting of the foliage. Damaged tissue can be affected by Botrytis, especially in mild and humid weather. Apply Elevate if damage has occurred and weather conditions are conducive for Botrytis development.
Figure 1. Foliar Phytophthora damage on a ginseng plant. Look for this damage on the edges of beds and in low areas of the garden. | Top of Page |
Cut Stems and the Creatures that Cause Them As we head into the growing season, you may be seeing evidence of seedlings that have been cut as they emerge through the straw. While this may make you instantly think of cutworms, there are actually a variety of creatures can cut the stems of ginseng seedlings. Here’s a quick review of each and how to distinguish the damage they cause. Cutworms, the immature stages of a family of night-flying moths, are perhaps most commonly associated with cut stems. They are usually active in the evenings, when they emerge from the soil to feed on stems (and sometimes leaves) of ginseng. Cutworm damage to stems can be distinguished by their habit of severing plant stems like a knife (Figure 2). The upper portion of the stem falls over and is often distinguishable by the severed leaves lying upside-down on the straw. Slugs are soft-bodied, slimy animals (essentially snails without a shell) which are more closely related to clams than insects. Like cutworms, they are also most active at night. In older gardens, slugs will chew holes in leaves, berries and taproots, but they will also attack the stems of seedlings. Unlike cutworms, which chew holes directly through the stem, slugs chew vertical holes in the side of the stem (Figure 3). Seedlings will not be completely severed, but rather bent over. Additionally, you may see evidence of a “slime trail” which is secreted by the slug as it moves. Mice will also chew on stems and exposed roots of ginseng. With mice, you often see elongated areas of chewing along the stem length, and like cutworms they can sever the stem (Figure 4). If you suspect mice, look for tunnelling beneath the straw, which they characteristically produce as they move along the length of the beds. Millipedes are only sporadic pests in ginseng, however on occasion they will attack seeds and emerging seedlings. As seedlings begin to extend above the straw, millipedes will chew them off where they break through the soil. Millipedes will chew anything that emerges, and not just the stem, so you will see a wider range of damage than with the other pests described. No discussion of feeding on ginseng stems would be complete without mentioning grubs! Grubs do not technically cut stems, however they do feed on young roots in seedling gardens. As they feed, the young plant is drawn down into the straw (Figure 5), so in contrast to cutworms the upper part of the plant is not left above the straw. Damage is most commonly seen in 2 year old gardens as circular empty spaces in beds, however at this point the grubs are typically not present in the garden. With ginseng we are most commonly focused on disease, however seedlings are also susceptible to damage by a variety of animal pests. When you see evidence of damage, it is important to properly identify the culprit, because control measures will vary with each one. | Top of Page |
Figure 2. Typical cutworm damage on a ginseng seedling. Note the leaf cut cleanly off the stem and lying beside the stem.
Figure 3. Slug damage on ginseng stems. Note that the stem has been chewed only half way through compared to the stem severed completely by cutworms.
Figure 4. Severed stems with long, elongated areas of chewing are indicative of mouse damage.
Figure 5. This seedling has been pulled into the straw by grubs. | Top of Page |
Growing Forward: Food Safety and Traceability Program Information Session Date: Tuesday, June 9, 2009 Join food safety representatives from OMAFRA and E-Biz for an information session on the Growing Forward: Food Safety and Traceability Program. This program is designed to help producers and processors adopt food-safety and traceability programs. Please bring your food-safety questions to the session. More information on the Growing Forward program is available at the following website: To register contact the Agricultural Information Contact Centre at 1-877-424-1300. This workshop will discuss what we are finding this spring in ginseng gardens and how to deal with pest pressures this season SIMCOE RESEARCH STATION AUDITORIUM NO CHARGE! To register call the Agricultural Information Contact Centre at 1-877-424-1300. 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. | Top of Page | |
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