Ligustrum Pest & Disease Issues
Topiary Pest & Disease Issues
Fungal Leaf Spot
These usually develop when environmental conditions are favorable for example when there is an excessive amount of moisture on the leaves of Ligustrum for an extended amount of time. Lesions will develop either at the periphery of the leaf or between veins and will spread from there. In time, leaf edges may become ragged as the necrotic tissue turns dry and papery. Infection of developing leaves and bracts results in puckered, distorted growth.
Control of this type of infection can be achieved by avoiding moist foliage of the plants. Prune large branches back and away from each other or if they are overlapping. Remove infected leaves and plants from the growing area and make sure to destroy the debris.
If the infection is increasingly difficult one may have to resort to chemical sprays and as always the label must be followed with precision.
Chili thrips are tiny, slender insects with fringed wings. They feed by puncturing their host and sucking out the cell contents. Certain thrips species are beneficial predators that feed only on mites and other insects. Pest species are plant feeders that scar leaf, flower, or fruit surfaces or distort plant parts.
Most adult thrips are slender, minute (less than 1/20 inch long), and have long fringes on the margins of both pairs of their long, narrow wings. Immature thrips (called larvae or nymphs) are similarly shaped with a long, narrow abdomen but lack wings. Chili thrips are dark in color as adults or light to translucent when juvenile.
Thrips prefer to feed in rapidly growing tissue. Feeding by thrips typically causes tiny scars on leaves called stippling, and can stunt growth. Western
Although chili thrips damage to leaves is unsightly, thrips activity does not usually warrant the use of insecticide sprays, however, oils are effective as a smotherant. For ornamental nonfood plants, a licensed pesticide applicator can use the systemic pesticides, but oils will provide control of adults.
Armored scales, family Diaspididae, have a flattened, platelike cover that is less than 1/8 inch in diameter. The actual insect body is underneath the cover. The covers often have a differently colored, slight protuberance. Concentric rings form as each nymphal stage (instar) secretes an enlargement to its cover. Armored scales do not excrete honeydew. Damaging species include Florida red scale and Oriental scale.
Soft scales can be smooth, cottony, or waxy and are 1⁄4 inch long or less. They are usually larger and more rounded and convex than armored scales. Their surface is the actual body wall of the insect and cannot be removed. Soft scales feed in the fluid-conducting phloem tissue of the plant and excrete abundant honeydew, which is sugary water that drips from their bodies. Soft scales include black scale, brown soft scale and mealie bug.
Females of many scale species reproduce without mating (there are no males). At maturity, adult females produce eggs that are usually hidden under her body or cover. Eggs hatch into tiny crawlers (mobile first-instar nymphs), which are yellow to orangish in most species. Crawlers walk over the plant surface, are blown by wind to other plants, or can be inadvertently moved by people or birds. They settle down and begin feeding within a day or two after emergence.
When plants are heavily infested with scales, leaves may look wilted, turn yellow, and drop prematurely. Scales sometimes curl leaves or cause deformed flowers and fruit.
Scales are often controlled by small parasitic wasps and predators including beetles, bugs, lacewings, and mites. Horticultural oils are specially refined petroleum products, often called narrow-range, superior, or supreme oils. Some botanical (plant-derived) oils are also available. Thoroughly spraying plants at the proper time with oil alone usually provides adequate control.
Slugs and Snails
Snails and slugs move by gliding along on a muscular "foot." This muscle constantly secretes mucus, which later dries to form the silvery "slime trail" that signals the presence of either pest. Slugs and snails are hermaphrodites, so all have the potential to lay eggs. Adult brown garden snails lay about 80 spherical, pearly white eggs at a time into a hole in the topsoil. They may lay eggs up to six times a year. It takes about 2 years for snails to mature. Slugs reach maturity after about 3 to 6 months, depending on species, and lay clear oval to round eggs in batches of 3 to 40 under leaves, in soil cracks, and in other protected areas.
Snails and slugs feed on a variety of living plants as well as on decaying plant matter. On plants they chew irregular holes with smooth edges in leaves and flowers and can clip succulent plant parts. They can also chew fruit and young plant bark. Because they prefer succulent foliage or flowers, they are primarily pests of seedlings and herbaceous plants
A good snail and slug management program relies on a combination of methods. The first step is to eliminate, to the extent possible, all places where snails or slugs can hide during the day. Boards, stones, debris, weedy areas around tree trunks, leafy branches growing close to the ground, and dense ground covers such as ivy are ideal sheltering spots. There will be shelters that are not possible to eliminate e.g., low ledges on fences, the undersides of wooden decks, and water meter boxes. Make a regular practice of trapping and removing snails and slugs in these areas.