Tomato issue

Clematis wilt symptoms. iGrow photo

By David Graper
SDSU Extension Horticulture Specialist

Q My Roma tomato plant wilted and died. Some of the fruit still ripened, but most have white blotches similar to those pictured. I removed the plant. Harvested the nearly ripe fruit. Is this fruit still ok to eat? Any special attention needed? What may have caused this? Upon cutting into one, the blotches continue into the fruit just under the skin, like it hasn’t ripened properly in these spots. Otherwise, the tomatoes look fine…just discolored and not completely ripe. Thanks!

A This appears to be a problem with a tomato spotted wilt virus (TSWV), which has been more common this year with the dry conditions because it is vectored by thrips, which are often more numerous during dry weather. There is no treatment for the disease once a plant gets it, other than to remove the plant from the garden. The disease does not make the fruit poisonous but it should not be used for canning. For more information see this article:

Clematis rapid decline

Q I have three clematis that almost look like they were sprayed! But nothing else around them was effected! I googled it and found that it’s probably a fungus. Untreatable. But the plants should grow back from the roots in the spring. I think, maybe, my dog has damaged the main stems and that’s how the fungus started.

A This appears to be a problem called clematis wilt. It is a fungal disease that starts out infecting the leaves and then under the right conditions it can move into the stems and cause a canker, which will essentially shut off the supply of water to the stems above the canker, causing a sudden wilt.

Clematis like to be grown in full sun but need to have their roots kept moist and cool by using a mulch or shaded by a surrounding ground cover. Heat and water stress can be particularly damaging to clematis.

There really isn’t any treatment for the problem, other than to provide a good growing environment and if the disease occurs, remove infested stems and foliage to reduce the chances of it coming back again next year. The plant may regrow from underground shoots, but there is no real way of knowing at this point. For more information see:

What kind of plant is this?

Q This plant was found in a garden. What kind of plant is this?

A This looks like a radish that has flowered and gone to seed. Most people will pull out their radishes once they begin to flower (also called bolting) because the roots become very spicy and often rather tough and woody, making them not very tasty. However, if the plants are left in the ground, after the flowers, these rounded, pointed fruit develop. The fruit is also edible but also rather spicy. Occasionally a plant may come up from seed as a volunteer and not be noticed until later in the season, after it has gone to seed like this.

Master Gardener training

Q I am interested in becoming a Master Gardener. Is there a training program available? If so, what all does it entail and will you give me the tools necessary to not kill my garden anymore? Also…do you allow unsuccessful gardeners to become Master Gardeners? Hopefully my track record would improve over time. Thanks for your time and I look forward to hearing from you!

A Yes, there is a training series that we do each year. We generally pick three sites to host the face-to-face training plus there are supplemental materials online as a D2L class. We usually start the class sometime from mid-May to the first week of June. This year we tried having 8 face to face sessions, 1 day per week and it worked out pretty well. Participants seemed quite pleased. I will add you to my list for next year but just so you know, we have chosen the training sites yet for next year. You will be notified when we have dates and locations firmed up, but information will also be posted to the website listed below. This year it was in Sioux Falls, Aberdeen and Spearfish. We normally do not have training in the same location two years in a row. You can learn more information about the program by checking out the information on this site.

Bonide Copper dust on tomatoes

Q Do you know anything about eating tomatoes after the plant was dusted? I do not see a waiting time on the label. On the computer I only see to wash the tomatoes off before eating, which to me is a given. Using my best Master Gardener trainee skills, I think I had(have) Septoria Leaf Spot.

A You are correct. According to the label, no pre-harvest interval is listed. It can be applied every 3 – 10 days as needed. However, it is not that effective on fungal diseases, it works better on bacterial diseases. If you are looking for another organic product to use, consider using sulfur.

Plant ID

Q Please identify this lily. It’s growing at Groton, SD. Thanks.

A This appears to be a plant most often called Magic Lily (Lycoris sqamigera) but is also known by a variety of other common names like surprise lily and even naked ladies. These common names refer to the growth habit of this bulbous plant. Foliage is produced in the spring and continues to grow until mid-summer, when it dies down to the ground. Then, usually in mid- to late-August, the flower spikes develop – a lovely surprise indeed. Lycoris is normally listed as being hardy to Zone 5 but I have seen it in a number of gardens in SD.

Powdery mildew

Q Powdery mildew seemed to take over my pumpkin and melon patch after the heavy August rains. Post harvest I typically bury all the vines in a single deep trench. What should I do with the infected vines or garden soils to minimize future out breaks? Also how harmful is breathing the powdery dust?

A Powdery mildew is a difficult disease to manage by disposing of the vines because the fungus produces tiny overwintering structures that start falling off the leaves, petioles and stems as weather cools in the fall. These cleistothecia are dark brown, small (diameter of about 0.003 inches) structures that are barely discernable without a hand lens. They are able to withstand adverse weather conditions and contain numerous sexual spores that can overwinter and begin a new infection the following year. As you move around the old vines and leaves, the cleistothecia are spread around on the soil. Spores are also blown up from southern states to begin initial infection in plants.

The best control strategy is to plant resistant varieties. When you are looking for your seed next season, look for powdery mildew resistant varieties, they may be signified with the initials (PM) by their names. Scouting the planting early in the season, when plants begin to vine out is another important means of control so that you can then apply a fungicide containing chlorothalonil, sulfur or an ultrafine oil to the plants to provide protection.

I have not seen any information relating to the potential harmfulness of breathing in the dust, but wearing a dust mask would probably not be a bad idea.

For more information see:

Mark your calendars

Third Thursday at the Gardens, “New Plant Variety Review” Presented by: Chris Schlenker, Head Gardener & Christina Lind-Thielke, Assistant Gardener/Education Coordinator. Thursday, September 21, 6:30 pm , McCrory Gardens Education & Visitor Center, located at 631 22nd. Ave.

Join us for a walking tour of the gardens as we take an intimate look at some of the newest varieties of annuals and perennials that were planted out this year!

Extension Master Gardeners may earn up to 1.5 Continuing Education hours for attending this class.

This class is free and open to the public. To register, please go to