This tomato hornworm is being parasitized by beneficial wasps. Photo credit: Henry Crenshaw
Why would anyone allow dozens of wasps to thrive in their garden? Why would they let caterpillars keep moving through their pepper bushes? Don’t they know you can spray for that?
As Extension agents, one of the tenets we “preach” in gardening is the concept of Integrated Pest Management (IPM). This technique involves a series of insect control measures that begin with the “least toxic” method of control, using chemicals as a last resort. One of those least toxic measures is “biological control”, in which a natural predator or parasite is recognized and allowed to remove a pest insect naturally. It is important to be able to recognize some of the more common garden predators and parasites. Many times these insects look strange or dangerous, and they are mistaken for pests and killed.
One such beneficial insect to the home gardener is the braconid wasp (Cotesia congregatus). Most people shudder at the mention of wasps, but these tiny (1/8 inch long), mostly transparent wasps are of no danger to humans. Quite the opposite–they are an excellent addition to gardens, especially if you are growing tomatoes or peppers. One of the major pests to these favorite vegetables is the tomato hornworm (Manduca quinquemaculata), a fat green and white-striped caterpillar.
The beneficial wasp can control hornworms because females lay eggs under the caterpillar’s skin, after which the eggs hatch and larvae feed on the hornworm. After eating through the caterpillar, they form dozens of tiny white cocoons on the caterpillar’s skin. The tomato hornworm is rendered weak and near death, and the vegetable crop is saved.
If you happen to find a tomato hornworm covered in these small oval cocoons, consider yourself lucky. Let the process continue, allowing the new generation of beneficial wasps to hatch and continue their life cycle. They will control any future hornworms in your garden, and the whole process is fascinating to watch!
For questions on integrated pest management, beneficial insects, or growing peppers and tomatoes, call your local County Extension office.
A few months ago I visited a property that had been renovated to clean up some limbs that were in danger of falling on the house. Pruning tree limbs that are in danger of hitting a structure is always a good idea, but it’s important to look at the impacts this practice may have on the rest of a landscape. Any time the light profile of a landscape is changed, current and future plant selection must be considered. One often seen example occurs when trees grow to full size and shade out the lush lawn that’s underneath. However, in this case, removal of limbs allowed more light to shine on some beautiful, old camellia bushes.
Camellia Planting and Care
Camellias do best in locations that receive filtered sunlight and are protected from the wind. They like acidic, well-drained soils. Trees and shrubs are generally planted 2″ to 3″ above the soil grade. (2″ to 3″ of root ball should be exposed above the soil grade when the tree/shrub is planted.) To help improve root oxygen exposure and help prevent a root rot situations, camellias can be planted slightly shallower than the previously stated recommendation. For more plant establishment guidelines, please visit: UF/IFAS Planting and Establishing Trees Guide
Scenario and Diagnosis
As mentioned above, the property in question was visited to diagnose sick camellia bushes. Upon further inspection of the property, asking about recent changes to the landscape, and inspecting the bushes, it was clear that the camellias were receiving too much sunlight. Sunlight damage was expressed by large brown sunscald spots on the yellowing leaves.
Sunscald damage on camellia leaves. Photo Credit: Jed Dillard
The camellias had also been pruned incorrectly. Camellias require minimal pruning. They are normally pruned to control size or promote a tree form structure if desired. Any pruning should be done before flower buds form in late summer.
An incorrectly pruned camellia bush. Photo Credit: Jed Dillard
Solution
The best solution in this scenario was to dig up the affected camellias and move them to a location with more shade. Sun loving shrubs were suggested as options to replace the camellia bushes. It’s important to note that Camellia sasanqua cultivars are usually more tolerant of sunlight than Camellia japonica cultivars. The recommendations were based on the Florida Friendly Landscaping principle of “Right Plant, Right Place”.
If you’re trying to find the right plants for you own yard, then you should check out the Florida Friendly Landscaping Interactive Plant Database. The database gives you plant selection options for each area of your yard based on location in the state, plant type, and soil and light conditions.
Chaste tree. The showy chaste tree makes an attractive specimen as the centerpiece of your landscape bed or in a large container on the deck. Easy-to-grow, drought resistant, and attractive to butterflies and bees, Vitex agnus-castus is a multi-stemmed small tree with fragrant, upwardly pointing lavender blooms and gray-green foliage. The chaste tree’s palmately divided leaves resemble those of the marijuana (Cannabis sativa) plant; its flowers can be mistaken for butterfly bush (Buddleia sp.); and the dry, darkened drupes can be used for seasoning, similar to black pepper, making it a conversation piece for those unfamiliar with the tree.
Vitex , with its sage-scented leaves that were once believed to have a sedative effect, has the common name “Chastetree” since Athenian women used the leaves in their beds to keep themselves chaste during the feasts of Ceres, a Roman festival held on April 12. In modern times, the tree is more often planted where beekeepers visit in order to promote excellent honey production or simply included in the landscape for the enjoyment of its showy, summer display of violet panicles.
Chaste tree is native to woodlands and dry areas of southern Europe and western Asia. It will thrive in almost any soil that has good drainage, prefers full sun or light shade, and can even tolerate moderate salt air. Vitex is a sprawling plant that grows 10-20 feet high and wide, that looks best unpruned. If pruning is desired to control the size, it should be done in the winter, since it is a deciduous tree and the blooms form on new wood. The chaste tree can take care of itself, but can be pushed to faster growth with light applications of fertilizer in spring and early summer and by mulching around the plant. There are no pests of major concern associated with this species, but, root rot can cause decline in soils that are kept too moist.
Versatile, easy-care, beautiful, native – what’s not to love about muhly grass?
Muhly grass is a hardy landscape choice with dramatic fall blooms. Photo credit: Carrie Stevenson, UF IFAS Extension
How is it versatile? It makes a perfect border along a fence or structure. Plant it in a single or double row depending on available space. Use a single plant as a specimen in a smaller landscape. Muhly grass can also be planted in mass to serve as groundcover in a larger landscape.
What makes it easy-care? Since it only grows into a 3-foot-tall mound, there is no need to continually prune it as you would have to do for many landscape shrubs that serve a similar function. Plant muhly grass in areas where you only want to have plants grow to a 3-foot height, such as under windows or along a short fence. This clumping grass can be pruned in late winter to remove dead leaf blades, but it is not necessary. There are few pest and disease issues and its’ fertility needs are low. This tough plant can handle both drought and inundation with water. Perfect for a rain garden! Flowering is best in full sun, but it can take part sun as well.
What’s so beautiful about a grass? In the fall, abundant pink to pinkish/purple blooms cover the canopy of the grass and add color to the fall landscape. The wispy blooms move with the breezes and add interest with their movement. The new cultivar ‘Fast Forward’ blooms as early as August and into the winter. If pink is not your color, there is a form with white blooms known as ‘White Cloud’.
Consider adding some muhly grass to your landscape. You will love it as I do.
Hydrangea leaf spot disease Photo credit: Larry Williams
It is not uncommon to see leaf spots on your hydrangeas during late summer and fall.
These spots are caused by a number of fungal diseases. Plant fungi and wet weather go hand-in-hand. Florida’s high humidity, heavy dews and frequent rains during spring and summer provide perfect conditions to allow fungal diseases to flourish. Bacterial leaf spots can be part of this foliage disease mix, too.
Common foliage diseases seen on hydrangeas this time of year include Phyllosticta leaf spot, Target leaf spot, Bacterial leaf spot, Botrytis and Cercospora leaf spot.
These foliage diseases are the norm rather than the exception as we move into the wet summer months and on into fall. As a matter of fact, you would be hard-pressed to find any hydrangea in our area without some evidence of infection now.
This late in the year it is more of a “grin and bear it” problem. In other words, it’s too late to do much about the fact that your hydrangea plant has leaves covered in ugly spots. By now many of the infected leaves are turning brown, withering and dropping prematurely from the plant.
Cercospora leaf spot is one of the most common foliage diseases of hydrangeas. Along with most of the leaf spot diseases, it begins as small dark-colored specks on the leaves. The small specks generally go unnoticed. But as the spots continue to slowly enlarge, mostly maintaining a circular shape, they become more obvious. With heavy infection, individual spots can coalesce forming larger irregular shaped brown areas on individual leaves. The individual spots may have a purplish halo with gray center.
There are some fungicides that can help prevent these leaf spots. But you’d have to begin treatment early in spring before any leaf spots exist and spray the plant every 10 to 14 days during favorable disease development (humid, rainy weather), which is pretty much our spring and summer months. These types of diseases are prevented, not cured. That’s the “grin and bear it” part of waiting until now.
The fungus survives on infected leaves. So, the best thing to do now is to remove and dispose of infected leaves. Also, be careful to not wet the leaves when irrigating the plants during the growing season.
New leaves of spring should be spot/disease free as they emerge. But the cycle of life for these leaf spot diseases will again result in spotted/diseased leaves on your hydrangeas next summer and fall without persistent treatment.
The good news is that these leaf spot diseases normally do not cause permanent/long-term damage for hydrangeas. They just make the plant look ugly.
A very popular landscape shrub installed by both professionals and homeowners is Loropetalum or Chinese fringe. This shrub offers attractive foliage and flowers along with being evergreen.
When you visit a nursery to select this plant for your landscape, realize that there are now many selections of Loropetalum available. Learn about a few of the common selections in this recording of ‘In the Garden’, with UF/ IFAS Extension Escambia County Horticulture Agent Beth Bolles, so that you are successful at matching the appropriate plant with your landscape needs.
