Plant Diseases / Pests
Plant diseases | Plant pests | Plant weeds | Lawn diseases | Lawn pests | Lawn weeds
The complex environment of living plants and other organisms present in your landscape provide the "home" for a wide variety of diseases and insects. Some of these "pests" can prove troublesome if not treated or removed. The following list of common problems should help you recognize and take steps to combat the "critters".
The most critical factor in your newly seeded lawn is water. Water softens the exterior ends of the seeds and allows the germination process to begin. The ideal germination conditions for optimum development is warm, moist soil.
"Shot Hole" Fungus
Fruiting and ornamental varieties of plum and cherry trees are susceptible to this disease which creates small holes in the leaves, sometimes in large quantities. Shothole is very common especially in very wet areas. It is generally not fatal but it is unsightly. Fungicide applications during the growing season provide control.
Mildew
A powdery white substance present on the leaves and buds of plants like roses, lilacs, and exbury azaleas indicates mildew was developed during warm, humid conditions. Leaves of the affected plants tend to curl up. Fungicide applied during the growing season will help control the disease.
Anthracnose
This is a common problem with Dogwood trees. Brown blotches along the mid-vein of the leaf are indicative of the disease. Especially damaging after a very wet spring, leaves often fall off and the disease can move into the branches. Pre-bud break fungicide applications are recommended along with removal of affected branches.
Verticillium Wilt
This is an incurable disease that can slowly kill ornamental trees like the very popular Japanese maple varieties. A branch will suddenly die on an infected trees and others will slowly follow. The soil around the tree should be considered contaminated and trees of the same variety or specie should not be replanted.
Blackspot/Rust
Roses and Photinia are common hosts for this disease. Leaves turn yellow or "black" and fall off. A fungicide on the affected plants will help control this disease.
Rootweevil
All the lifecycle stages of this pest can damage plant material. These black or brown adult insects, about 1/4" long, chew the edges of leaves during the summer months. This "notching" is not fatal but should alert you to the fact that the adults will soon lay eggs. The larva, or grubs, will cause severe damage if left untreated. During the spring the grubs can "girdle" the trunk of a plant and/or destroy the root zone very quickly. These pests move from plant to plant rapidly so treatment(s) with an insecticide is important.
Leaf Miner
Birch trees are a common host for this small caterpillar. Leaves may roll up or have patches missing as this insect chews it’s way through your trees. Several applications of insecticide are required to rid your trees of this pest.
Spidermite
These reddish brown mites seem to prefer tightly branched evergreen plants. If you notice yellowing of the foliage, the spidermite may be present. To check for the mite, hold a white piece of paper under a branch or branches, shake the branches over the paper and then rub or smear your hand over the paper. If reddish streaks appear on the paper, you have mites! Systemic insecticides work well on this critter.
Slugs
The telltale "slimy" trail of this nocturnal mollusk probably means a feeding frenzy on your favorite plants. As evidenced by holes in the foliage, slugs can be very destructive to succulent plants. Slug bait encircling the plant can stop them in their tracks.
Aphids
These small soft bodied insects of various colors, can suck the life out of your plants. A shiny, sticky secretion on the foliage can indicate a problem, especially on new growth. Give them a blast of water to remove them from the plant or repeated applications with an insecticide may be needed for longer control.
Tent Caterpillars
This pest is very obvious from the unsightly "tent" formed high up in the host tree or shrub. Seldom fatal, the most efficient control is removal by cutting out the tent.
Not a Disease or Pest — it’s Sunscald
This is often mistaken for disease or bug problems, but browned curled leaf margins may be the result of intense heat. Make sure that the plant is getting enough water and remove the affected leaves to allow new growth to generate.
A wide variety of "broadleaf" and "grassy" weeds can germinate in newly tilled soil. "Contact" weed killers, like "round-up" can be useful in controlling most weeds already present in the shrub beds. Be careful not to get the spray on the foliage of your plants! As a "pre-emergent" control, "Casoron" and "Rhonstar" are common granular products for weed control applied in February and November. Don’t use "Casoron" near lawn as it will kill grass plants.
Redthread
The most common lawn disease, it appears as yellow patches turning brown that are held together by red or pinkish webbing on the grass blades. It is usually a symptom of low fertility which requires treatment with a high nitrogen fertilizer. Maintaining a consistent fertilization program will help prevent recurrence.
Cranefly
The larval stage of this insect appears in the spring with an appetite! Patches of grass will die out or look faded as the roots are devoured by the chewing grubs. The 1/2" long grubs are brownish with black heads. Usually spring and fall applications of insecticides are recommended. The adult cranefly has wings and looks like a giant mosquito.
Moles
These voracious mammals can destroy your lawn or shrub beds in a short period of time. Moles are extremely difficult to eradicate. Trapping may be the most successful, yet frustrating method to rid your yard of the critters causing the dirt piles and soft "tunnels". Perhaps a professional service is in order for a significant population.
The most common weeds are broadleaf varieties like dandelion, clover, spurge, and plantain. They are best controlled with contact herbicides available at most garden shops. Read the directions carefully for the correct mixture. Sometimes "grassy" weeds invade a stand of grass. Lighter color or different texture grass must be killed first and the area re-seeded or re-sodded. Unfortunately, in our climate, the invasive grasses commonly germinate and contaminate our otherwise uniform lawns.