Several species of aphids are pests of annual and perennial plants and pop-up in a variety of colors including white, yellow, red, green, and brown.

Damage

Aphids are sap suckers that reside in buds, the underside of leaves, and on developing stems. Extreme infestations can result in loss of vigor and distorted growth.

Treatment

Use Neem Oil and Insecticidal Soap for low density infestations. Eight and Captain Jacks Dead Bug Brew are also good options for residual sprays when the problems become large scale. Simply hosing off or pruning away infected plant parts can also be effective.

Slugs are a soft-bodied elongated pest that lives in cool, wet places in the shade. They often feed on Hostas but will venture and feed on a wide variety of herbaceous plants. Slugs usually live throughout the winter as eggs under plant debris, mulch, or in soil beds. Once spring arrives, eggs hatch and feeding begins. Large populations can result in a slug problems through the end of the summer.

Damage

Slug damage resembles hail damage, numerous small holes in the leaves the size of pencil erasers or even marbles.

Treatment

Sprinkle Sluggo or Sluggo Plus on the soil surrounding affected plants and areas.

Japanese beeltes are not only destructive, but they also excel at making gardeners miserable. Their favorite foods include roses, raspberries, grape vines, and linden trees. They’ve been seen on dogwood and Echinacea, and several annual plants such as hibiscus and potato vine to name few. Be out there watching for beetles to emerge in late June through early August.

Damage

Japanese Beetles will eat and devour the leaves, flowers, and fruit of up to 300 plant species causing lage holes or even lace like leaves where all tissue has been removed and only leaf veins remain.

Treatment

Hand pick and toss beetles into a bucket of soapy water. Do this a couple times per day when they first emerge because new beetles will continue to hatch throughout the growing season.

Bonide’s Japanese Beetle Killer, Eight, and Captain Jack’s Dead Bug Brew are effective insecticides. Spray very early in the morning or late in the evening when pollinators aren’t actively foraging and avoid spraying blooms for pollinator safety (if possible, enclose blooms in baggies for extra protection), and try to hit the beetles directly.

Beetle baggers are another option. It’s true that the bagger attracts beetles, so your neighbor’s beetles might end up in your yard. However, the point is to place away from their favorite plants to lessen the damage plus kill the beetles and stop them from laying eggs.

Powdery mildew is a common fungal disease caused by a group of both specialist and generalist fungi. Powdery mildew spores travel easily through wind and contact, quickly germinating once in contact with the leaf surface with or without water present. Powdery mildew prefers warm, dry days for spread and cool, humid nights for spore production. This fungus spreads quickly in shady areas of poor air circulation and high humidity. Powdery mildew infects the buds of woody plants, surviving on leaves of evergreen plants, and through production of specialized overwintering structures. While powdery mildew disease is rarely fatal and largely a cosmetic issue, it can impact growth and development in particularly severe infections.

Signs

White or gray web-like or powder-like spots on upper leaf surfaces and stems. Very small, black, or orange structures on affected leaves and stems.

Symptoms

• Yellowing leaves and leaf drop
• Stunted or disfigured tender growth
• Bud abortion
• Purple or red leaf coloration

Handling and Treatment

• Remove affected leaves if early signs of infection are detected.
• Keep plants well-spaced
• Water at the base of plants and avoid wetting foliage as much as possible
• Thin out overgrown, dense foliage to increase airflow
• Treat with Copper and Sulfur Fungicides as preventative, Fungonil in extreme cases for curative purposes. Neem Oil may have some curative affect

Plants to Watch

Peony

Monarda

Veronica

Astilbe

Ninebark—especially severe if infected

Echinacea

Pulmonaria

Coreopsis

Salvia

Fungal leaf spots are a very common issue in herbaceous perennials as well as for trees and shrubs and are caused by a wide array of largely specialist fungal pathogens. Fungal leaf spots or lesions begin as discrete sections of leaves that may appear dull green or yellow in color, later turning brown or black and eventually becoming necrotic. Fungal leaf spot shapes vary greatly based on host and pathogen, but are generally oval, oblong, or round, often appearing target-like, and may coalesce into large diseased areas of foliage. Twigs and branches may also become infected and develop sunken, discolored, and cracked areas in the woody tissue called cankers. Like other fungal pathogens, fungal leaf spot pathogens generally thrive in hot, humid conditions and require either extended periods of high humidity or a film of water for germination. Leaf spots generally mature in one to two weeks whereafter spores can be easily spread through wind, water, and contact. Leaf spot pathogens generally thrive in shadier areas with low air circulation and overwinter as specialized structures or mycelium on infected plant material or plant debris.

Signs

Black or red dots within lesions on upper leaf surfaces. White or gray wispy growths (mycelium) present on upper leaf surface.

Symptoms

• Dull green or yellow translucent spots turning brown or black which eventually coalesce
• Leaf drop
• Stem cankers
• Deformed leaves, stems, and buds

Handling and Treatment

• Remove affected leaves if early signs of infection are detected
• At or before signs of early disease development, Revitalize fungicide application can help reduce disease spread
• Keep plants well-spaced
• Water at the base of plants and avoid wetting foliage
• Thin out overgrown, dense foliage to increase airflow
• Keep plant growing areas free of leaf litter and other detritus and frequently check plant pots for dead leaves on the soil surface
• Copper and Sulfur fungicides may have curative effects.

Plants to Watch

Echinacea

Rudbeckia

Peony

Aster

Roses

Lilac

Hydrangea

Make note of the timing of garden pests and disease. Where is the problem? When did it first appear? What worked and what didn’t in attempting to fix the issue? Next year, review your notes at the beginning of the season and be ready to tackle any issues.

Bee careful, bee safe. Keep our pollinator pals in mind when choosing what to treat the problem with and how to treat it. 

Don’t become too disheartened over bug and disease problems - it’s unfortunate, but it’s just part of gardening.

If you are feeling overwhelmed or have specific questions, we are always here to help. Email us your questions - hello@tonkadale.com - photos help!