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    Save the Date: Perennial Plant Society’s 30th Plant Sale is April 4, 2020, 9 a.m. – 1 p.m. at the new Expo 3 Building at The Fairgrounds Nashville. Here’s where you can find the newest varieties of perennials, shrubs, vines and annuals from local growers, along with long-time, never-fail favorites, ready for spring planting. Learn more at the PPS website.

     

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Holes in your hostas? Suspect slugs

The hostas in my shade garden are ragged and full of holes every year at the end of summer. Is this normal?

HostaIt’s not unusual to find holes in big, leafy hostas. Those large, wide leaves create a cool, moist shelter for slugs and snails, who may rest under them during the heat of the day and come out at night to dine. You can verify their presence by placing a small board beside the hostas where you’ve noticed damaged leaves. In the morning, turn the board over to see how many have gathered on the underside of the board. Dispose of them as you wish. Another option may be to set out a small dish or a shallow aluminum can (such as a tuna or cat food can) filled with beer beside the hostas. Slugs in the area may be lured by the beer to crawl into the can, and you can dump them all in the trash.

The American Hosta Society suggests several solutions for protecting plants from slug damage, one of which is to provide something else for them to eat, such as lettuce. A different strategy focuses on placing a barrier around vulnerable plants. Strips of copper on the ground can be effective because slugs don’t like to cross it; diatomaceous earth or table salt sprinkled around the plants also may keep them away, but be careful about adding too much salt to the soil.

The American Hosta Society mentions a couple of poison baits, but also suggests that a 10% solution of vinegar, sprayed on the slugs, stops them in their tracks – but you have to be out there with the spray when they are out, which is usually at night.

A final suggestion is to set a trap. Place two boards together with a small stick between them, where the slugs can crawl into the cool shade. Then, when the slugs are between the boards, remove the stick to trap and dispose of them.

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The Nashville Tree Foundation announces the opening of the Betty Brown Tree Trail and Arboretum, a leafy respite next to the newly developed Riverfront Park and Ascend Amphitheater in downtown Nashville. The meandering trail, Named after

Betty Brown

Betty Moorhead Brown

NTF’s founding board member and first president, the late Betty Moorhead Brown, includes 236 trees representing 36 different species. A dedication ceremony is planned for later this month, but Nashville Public Television’s Volunteer Gardener program has already taped a segment at the Trail. The segment will air on Sept. 17 at 7:30 p.m. and again on Sept. 20 at 9:30 a.m.

For visitors to the Trail, Nashville Tree Foundation has developed a guide pamphlet that lists the tree species and what to look for along the way. When you visit, pick up a pamphlet at the visitor’s kiosk, or download it here at NTF’s website.

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In The Tennessean — Easy design with herbs: Floral designer Ralph Null has a simple rule for arranging flowers: “My whole approach is what I call easy design.” He will be among the speakers at the Herb Society of Nashville’s annual Herb Day on Sept. 19, and offers tips for using herbs in floral designs in a story in Saturday’s Tennessean.

Mealybugs make a meal of houseplants

One of my jade plants has some sort of white fluff on the stems. Is this normal?

Jade plant

Jade plant is one of many houseplants that can be affected by mealybugs.

White fluff is not normal. Your jade plant is no doubt hosting an infestation of mealybugs, tiny sap-sucking insects that will damage the plants if they are left to multiply. They appear as small, cottony growths on the stems and leaves of jade plants and many other houseplants. They do their damage by inserting their piercing mouthparts into the plant’s tissue and extracting the juices.

Mealybugs thrive in a warm, dry environment – such as inside a home in winter. Female mealybugs don’t fly, but once established on a plant, they can find their way to nearby houseplants so it’s good to get rid of them as quickly as you can – not always an easy task, because that fluff is rather waxy and resistant to pesticides.

The best way to begin to eradicate the insects is to remove them by hand. Dip a cotton swab in rubbing alcohol and wipe them off. You may have to do this two or three times until all the unseen eggs that may have been deposited have hatched. If the infestation is heavier, follow up with a spray of insecticidal soap.

Always be watchful for insects to reappear, and try to get rid of them quickly. In addition to jade plants, mealybugs may find their way onto African violets, ferns, pothos, Norfolk Island pine, schefflera, diffenbachia, pothos, philodendron and many other popular houseplants.

Mealybugs are a common problem, and information is readily available. The North Carolina State University Cooperative Extension provides information here.

Stinkbugs, harlequin bugs plague late-summer gardens

There are flat, brightly colored bugs all over my cabbage and broccoli plants right now. What are they? Are they harmful? How can I get rid of them?
Harlequin bug copy

What you see plaguing your plants are, no doubt, harlequin bugs, and yes, they are harmful to your plants in the brassica family – broccoli, greens, cabbage turnips and kale. This time of year, the bugs you see are probably the adults. They use piercing mouth parts to extract the juices from all parts of the plants, and heavy infestations can cause severe damage – you may see discolored spots on the plants. The leaves of young plants may wilt and die, and mature plants will become stunted.

Getting rid of them can be a challenge. Toxic Free NC, A website devoted to non-toxic solutions to pest problems, suggests removing them by hand if there are only a few (drop them into a bucket of soapy water), or if there are large numbers and you are willing to sacrifice the plants they have damaged, trap them in large garbage bags, seal the bags and let them bake in the sun for a few days.

It’s always good to encourage the natural predators of damaging insects to visit the garden. Praying mantises eat harlequin bugs and other stinkbugs, so if you see them around, don’t shoo them off. There are parasitic flies and wasps that are among stinkbugs’ natural predators, and birds, spiders and toads also enjoy them as a food source.

As a last resort, Toxic Free NC suggests insecticides that are approved for organic farms, such as rotenone, pyrethrin, Neem oil and insecticidal soap. Note that these products can be harmful, so be sure to follow label directions and use as little as possible. These insecticides can also kill the bugs you want to keep, so spray only in the morning or late evening when those insects may be less active. Insecticides are most effective on the pests in the younger larval or nymph stages. The adult bugs are resistant to sprays.

To prevent the bugs from finding your plants in the first place, Toxic Free NC suggests using lightweight floating row covers over your brassica crops, making sure the edges are weighted so the bugs can’t get to the plants. It also helps to control weeds in the garden, as stinkbugs are attracted by weedy areas in or near the garden, they advise.

Japanese beetles fly in to dine on your garden

I’m having a problem with Japanese beetles. I have beetle traps hanging around my garden and they catch a lot of them, but beetles are still chewing on my wisteria and rose bushes. I don’t want to spray, so every day I hand-pick them off. What else can I do?

Japanese beetle feeds on canna flowers.

Japanese beetle feeds on canna flowers.

Those Japanese beetle traps work by using a chemical that mimics a pheromone produced by the female Japanese beetle to lure the male beetles. You now see how well this works, as you are drawing more and more Japanese beetles into your yard where, on the way to the trap, they stop to dine on your plants.

Extension agents say that if you use these traps, it’s best to place them a good distance from any plants you want to save, so they will be lured away from the plants.

Generally, most experts advise against using them at all.
Good for you for choosing not to spray chemical killers – the honeybees and other pollinators are safe in your landscape. Handpicking the beetles or knocking them off into soapy water is an effective short-term method for reducing the population in your garden. The best time of day may be early morning, when they apparently are more sluggish.

Biological control of Japanese beetles begins with understanding their life cycle. Young grubs hatch in the soil in late summer and feed on roots, then spend winter in the soil. They become active in spring and continue to feed. Adult beetles begin to emerge in June.

You can treat the lawn with milky spore, a bacterium that kills the grubs in the soil. Milky spore builds up in the soil over several years and suppresses the grub population over time — no grubs, no Japanese beetles to hatch and harass your plants.

The University of Tennessee Extension has a publication about controlling Japanese beetles. You can read it here.

Good bugs vs. Bad bugs

Question: I have found several big green caterpillars covered with something that looks like white eggs on two of my tomato plants. What are they? How can I get rid of them?

A tobacco hornworm covered with wasp cocoons, and one without.

A tobacco hornworm covered with wasp cocoons, and one without.

What you are seeing is a good example of Nature helping you to control some of the pests in your garden. The green caterpillars are tobacco hornworms, which can chew up big portions of a healthy tomato plant before you even know they’re there. The white things are the cocoons of braconid wasps, parasitic wasps whose larvae feed on the hornworm, ultimately killing the caterpillar. The wasps, which are very small and not a stinging type, are considered beneficial insects in large-scale agricultural production and in home gardens.

Here’s how it works: A female braconid wasp lays eggs under the skin of a hornworm. The eggs hatch, and the larva begin eating the caterpillar’s insides and chew their way out through the host’s skin when they mature. On the outside, they spin the little oval cocoons along the caterpillar’s back and sides. By the time the adult wasps emerge, the hornworm is weakened and will soon die.

If you see a green hornworm on tomato plants – and they’re hard to spot, being exactly the color of tomato leaves! – pluck it off and dispose of it. But if you find one with white cocoons all over its back, leave it in place. It’s hosting another generation of parasitic wasps that will seek out and destroy hornworms on your tomatoes.

A sticky hackberry situation

QUESTION: We have a question regarding one of our large hackberry trees. It’s covered with little white flying bugs and the leaves have a sticky residue. What causes this and is there something that we can do about it?

Asian wooly hackberry aphids are a nuisance, but won't harm the trees.

Asian wooly hackberry aphids are a nuisance, but won’t harm the trees.

The bugs you are seeing are called Asian wooly hackberry aphids, and they seem to make an appearance about this time every year. They feed exclusively on hackberry trees, and like all aphids, they feed by piercing the leaves and extracting the juice. The sticky residue is what they excrete after feeding on the leaves, a substance called honeydew. Another byproduct you may notice is a black mold that grows on the honeydew, which is called sooty mold.The aphids apparently do not do enough damage to harm the tree, they are just a nuisance, mostly in late summer and early fall when their population grows due to the many generations that have been produced. If it’s a nuisance you can’t tolerate for some reason, there is a systemic insecticide product that is said to be effective in controlling aphids, but it would not do anything to solve this year’s population. There are several brands available, but the main ingredient is a chemical called imidacloprid, and it should be applied to the ground around the tree in early spring, where it will be taken up via the tree’s vascular system into the leaves.

Not much, then, can be done about this year’s population of hackberry aphids. Hose off the cars, the deck, the lawn furniture and anything under the trees that are sticky from the honeydew, and take comfort in the knowledge that they are a temporary annoyance, and will be gone in a few weeks.

Lovely roses, ugly leaves

QUESTION: I have two rose bushes and the flowers are beautiful, but there are small, irregular holes in some of the older leaves. My neighbor’s roses have black spots on the leaves. What causes these things?

rose redThere seem to be so many things that can bug roses: aphids, spider mites, Japanese beetles, thrips. Blackspot, anthracnose, mildew.

Damage to leaves is most often caused by insects. If you find holes in the leaves of your rose bushes, most likely they have been visited by the chewing kind. One likely suspect may be the little caterpillars known as rose slugs, the larva of an insect called a sawfly.

A little research reveals that the adult lays her eggs on the leaf surface, and when the larvae hatch they move to the underside of the leaf and begin feeding, creating holes between the veins. Finally, the larva drops to the ground, and later emerges as an adult sawfly, ready to begin the cycle again. There can be six generations a year.

Rose holesThe best method for eradication is to pluck these things off the leaves when you see them. Examine the undersides of the leaves, particularly, for the ¾-inch, lime green caterpillars. If you feel you must spray something, a pyrethrin product is advised.

The black spots on rose leaves could be one of several possibilities: Anthracnose is a fungal disease that causes black spots that later turn purple or brown. It thrives where conditions are moist. Downy mildew begins with irregular purplish spots that turn black. The most common, though, is a condition called blackspot, another fungus that thrives in moist conditions.

These diseases overwinter on old leaves that fall to the ground, so it’s good gardening practice to clean up around the base of the shrubs and remove dead foliage. The experts at the Nashville Rose Society recommend a regular fungicide spray schedule beginning in the spring.

With all that can go wrong with roses, why bother growing them? Because if you have the right sun and soil conditions, they can be one of the most rewarding plants in the garden.

Eating extra-local — from your back yard

Find ideas for all that zucchini, that basket full of okra, all those tomates, plus summer garden tips and tasks in the August Garden Calendar at Tennessean.com.

Garden events in Middle Tennessee

August 20: Julie Berbiglia of NPT’s Volunteer Gardener is the speaker at this month’s Perennial Plant Society of Middle Tennessee meeting at Cheekwood’s Botanic Hall. Her topic: “Water Conservation.” Refreshments at 6:30, meeting at 7 p.m. The public is invited. www.ppsmt.org.

August 22: Hosta hybridizer Bob Solburg of Green Hill Farm in Franklinton, N.C. is the speaker at this month’s meeting of the Middle Tennessee Hosta Society at Cheekwood. The meet-and-greet begins at 6:30, meeting at 7 p.m., and Solburg will have plants for sale. www.mths-hosta.com.

What’s bugging the squash?

QUESTION: The leaves on some of my squash plants are beginning to wilt. Some of the small squash are rotting. What’s the reason?

squash gbWhen summer squash plants begin to go bad, you can probably blame it on insect pests. Two likely culprits: the squash bug and the squash vine borer.

“When squash leaves wilt and collapse, the squash bug is usually the pest to blame,” says extension agent David Cook. Squash bugs lay small, bronze-colored eggs on the undersides and upper surfaces of the leaves. Nymphs are gray with black legs, and are usually found in groups; adult squash bugs are broad and flat. They pierce the leaves and remove the sap, leaving the leaves wilted. You may also find them on cucumbers, melons and pumpkins.

The best control method is to be on the lookout for the eggs early in the season, and remove any that you find on the plants. (Organic Gardening magazine’s online pest control center suggests gently squishing them before they have a chance to hatch, and squishing any nymphs you may find, as
squash bug eggswell.) If you feel you must spray something, Cook says insecticides labeled for squash bug include bifenthrin, or permethrin. Always read and follow label directions.

If a long branch of the plant — or the entire plant — wilts suddenly, it’s the work of the squash vine borer, the larva of a moth that lays her eggs on the leaf stalks and vines. The eggs hatch in about a week, and the larva bores into the stem of the plant and begins to feed. If you look closely, you may find sawdust-like material near the base of the plant. To try to save the vine, split the stem open and remove the caterpillar. Mound soil up around the wound to encourage roots to grow.

After the larva enters the stem, insecticides are ineffective, so if you choose to use a chemical treatment, you have to start early. Cook says insecticides labeled for squash vine borer include bifenthrin, permethrin, carbaryl and esfenvalerate, and spinosad, which is considered a natural insecticide. Again, be sure to follow label instructions.

 

 

Aphids: a ‘green’ goodbye

My new tomato plants already have tiny green bugs on them. I think they are aphids. What can I put on the plants that is safe (no chemicals or poisons), but that will get rid of them?

Young tomato plants are vulnerable to aphid infestation.

Young tomato plants are vulnerable to aphid infestation.

You are probably correct that the tiny bugs are aphids. They tend to hang out in clusters on the tender new growth of many plants. If the infestation is heavy, it’s best to try to get rid of them because they use their piercing mouthparts to suck the plants’ fluids – a bad start for struggling new tomato plants.
Many garden information sources suggest knocking the bugs off with a strong spray of water. Spray all parts of the plants, including the undersides of leaves. One of the reliable resources I use, Rodale’s Vegetable Garden Problem Solver, suggests blasting them with the water spray twice a week. They also suggest a garlic or hot pepper spray to deter the bugs, either a commercial product or a concoction that you make at home.
As a last resort, spray the plants with insecticidal soap. There are several commercial brands available (Safer is one that is commonly found at nurseries and garden centers), or make your own.
One recipe suggested by “green” garden expert Joe Lamp’l is this, from his book The Green Gardener’s Guide: Mix a teaspoon of dishwashing soap (not detergent), a teaspoon of cooking oil and one quart of water in a spray bottle. He adds a note of caution: “Insecticidal soaps can be phytotoxic (having a tendency to burn) to certain plants, so be sure to test a small area before applying on a larger scale.” Lamp’l also cautions that soaps are nonselective, and you may also be destroying beneficial insects, so use this solution sparingly.
Garden events in Middle Tennessee
May 21: Perennial Plant Society of Middle Tennessee meets at Cheekwood’s Botanic Hall. Speaker is Jimmy Williams from Paris, Tenn, on “The Perennial Border from February through December.” Refreshments at 6:30, meeting at 7 p.m.
May 23: Middle Tennessee Hosta Society meets at Cheekwood’s Potter Room, 7 p.m. Featured speaker is Jason Rives, owner of Petals From the Past in Jemison. Ala.; topic is “Incorporating Antique Roses into the Hosta garden.”
Fridays in June and July: Visitors to Cheekwood gardens can enjoy them in a new way on Fitness Fridays, with a variety of workout activities held in the gardens and on the grounds.
-7:30 a.m. Yoga in the Gardens, led by certified trainers from the Green Hills YMCA
8:30 a.m. Sculpture Trail Hike, a mile-long hike through Carell Woodland Sculpture garden led by certified trainers.
9:30 a.m. Stroller Strides, a vigorous workout for moms and dads up and down the paved driveways an din the garden.
Gates open at 7 a.m. Fitness Fridays are free to Cheekwood members; non-members pay the regular Cheekwood gate admission.

Slugs feel at home in the hostas

QUESTION: I have hostas in my yard that were beautiful all summer, but they are now riddled with holes. What could have happened to them?

The broad leaves of hostas lure slugs to the shade, where they also find a tasty meal.

When you find holes in your hostas, the problem most likely is snails and slugs say the experts at U.T. Extension. Hostas are shade plants, and slugs and snails are right at home in a shady, moist environment. The large, wide leaves create a shady spot, so they stay in that cozy spot all day and come out at night, climbing up on the leaves to dine.

If you want to see how active they are, try this: place a small board, about six inches wide, beside the hostas where you’ve noticed damage. In the morning, turn the board over and see how many have collected on the underside (and dispose of them as you wish). A gardening friend told me recently that she had set out an old tuna can filled with beer beside the hostas in her garden. The next morning, the can was full of slugs, and she dumped the whole thing into the trash.

The American Hosta Society suggests several solutions for protecting plants from slug dining damage, one of which is to provide something else to eat that might be just as tasty, such as lettuce. A different strategy focuses on placing a barrier around vulnerable plants. Strips of copper on the ground can be effective because slugs don’t like to cross it. Maybe that’s a way to use all those pennies that collect around the house. Table salt sprinkled around the plants also may keep them away, but you probably don’t want to add all that salt to the soil. My friend who lured slugs into a tuna can also said she has tried sprinkling diatomaceous earth around the hostas as a barrier they won’t cross.

The American Hosta Society mentions a couple of poison baits, but also suggests that a 10% solution of vinegar, sprayed on the slugs, stops them in their tracks – but you have to be out there with the spray when they are out, which is usually at night. And finally, a trap: place two boards together with a small stick between them, where the slugs can crawl in and hide in the cool shade. Then, when the slugs are between the boards, remove the stick and stomp. Ewww.