Your lawn is not the only vulnerable piece of your landscape. Perennials, shrubs, and trees also require careful observation to keep your landscape looking its best. In the Landscape Lowdown article, we discussed how to properly care for plants. In this article, we will be discussing some common diseases and pests and how to identify them.
Pests
Bagworms: This insect gets its name from the small protective bag of larvae that are attached to trees and shrubs. They are not abundant every year however once they attack a plant they become a persistent problem. Bagworms typically attack conifer evergreens but will also attack maples, oaks, and willows. Removing and destroying the bag is the best way to eliminate these pests but it is also the most time-consuming. Insecticides are available to treat bagworms however these sprays must be done at the first sign of bagworms and sprayed during ideal conditions.
Spider Mites: These insects are extremely small and difficult to spot. They prefer the underside of a plant’s leaves, making them even harder to notice. The oval-shaped insect feeds on the sap of plants. The damage caused by a feeding will leave yellow or brown speckles on the foliage. Webbing attached to the foliage can indicate a definite presence of spider mites. Sticking to a proper watering schedule and checking plants often are great preventative measures. If caught early enough a spider mite infestation can be treated using natural and/or chemical products. If you suspect spider mites, be sure to check all plants in this location for damage. In some cases, the infestation is so severe that the best course of action is to remove the infested plants.
Scale: Scale can vary in color, shape, and size. Scale feed on sap from plants, robbing the plant of vital nutrients. Once attached to the plant they cover themselves with a waxy material. Some leaves may have a shiny appearance and be sticky to the touch. Damage from the scale can also promote the growth of fungus. These insects thrive in warm dry environments and target the underside of leaves. The best defense against scale is to take preventative measures such as proper watering and fertilizing.
Japanese Beetle: One of the most destructive insects in our area is the dreaded Japanese beetle. They are not native beetles rather they were first found in the United States in 1916 with a shipment of tulips that arrived on the east coast. These beetles will attack everything from your lawn to your landscape to your vegetable garden. Adult Japanese beetles are known to feed on over 300 species of plants. By examining the life cycle we can better control future infestations. In order to effectively control this beetle we must stop the life cycle. Females will lay eggs in late July to August. The eggs will hatch in about 10 days. These grubs begin feeding on turf roots and continue feeding up to late October. The grubs will start feeding again in April. Applying a grub control product in August when the new grubs are hatching will reduce the beetle population for the next year. An insecticide can be used to treat adult beetles for the current year.
Diseases
Anthracnose: This is a group of fungal diseases that infect a wide variety of plants, especially trees. It causes dark lesions on leaves with premature leaf fall and can create sunken lesions and cankers on stems. These lesions can weaken the plant/tree leaving it susceptible to other diseases and insects. Anthracnose can survive on infected plant debris and spreads very easily. Spray the infected plant with a fungicide after all the infected wood and leaves are removed and destroyed.
Crown Gall: The bacteria (Agrobacterium tumefaciens) reside in the soil and stimulate the rapid growth of plant cells causing abnormal growths on roots, stems, and branches. The galls disrupt the flow of water and nutrients from the roots to the branches. This disruption reduces the overall growth and health of the plant. Secondary diseases can invade the plant through the cracks in the galls. Be certain to examine nearby plants as this bacteria can spread through the soil.
Root rot: A fungal disease usually caused by poor drainage. An infected plant will have mushy stems, yellow wilting leaves, and slow growth. The soil will smell rotten and the roots of the plant will be reddish brown. Preventative measures can be taken to reduce the chance of your plants contracting this disease. Once a plant is infected this disease is next to impossible to treat. The best course of action is to remove the plant and replace the soil in the area of the infected plant.
Cankers: This will occur when there is an injury (open wound) to a tree or shrub that then becomes infected with a fungal or bacterial pathogen. Cankers can kill branches and weaken the structure of shrubs and trees. There is usually a gummy substance and discoloration of the wood in the cankered area. Flower, fruit, and branch infections can become systemic, leading to twig dieback, death of larger branches, or even death of an entire tree. Prune infected branches a minimum of 12 inches below the canker. Prune only during dry weather and always sterilize your pruning tools between cuts.
Leaf Spot: A variety of diseases that occur on many species of shrubs and trees. Leaf spots can weaken the plant by interrupting photosynthesis. The spots start as small dark brown to black spots with a yellow halo. The smaller the spot the younger the infection. The pathogens are carried from one area to another by the wind and rain. Preventative measures are always the best option to limit the risk of disease. In the case of an infection remove and dispose of infected foliage and apply a fungicide.
Powdery mildew: This disease starts with small circles of powdery white spots. It can be found on the tops of leaves. This fungal disease likes warm (below 90 degrees) dry weather with high humidity. It affects plants in shaded areas more than those in the sun. Once plants are infected it’s difficult to eradicate this disease so concentrate on preventing the spread of the disease. Plant in sunnier spots, prune overcrowded areas, and water and fertilize as specified for your plants.
