A member of the wasp family, Sawflies are known for defoliation of roses and pines.

Damage

Sawflies causes windowpane-like damage to leaves which causes translucent, block-like specs between veins on the surface of rose leaves. In the case of pines, total defoliation can occur as well as needle brown out or yellowing.

Treatment

Eight or Captain Jack’s Dead Bug Brew.

A white, fluffy, and elusive species of aphids that are known to leave white webbing on the underside of leaves, on stemsof plants or near the crown of roots. Adults are winged, meaning that they can skrrrrt from leaf to leaf, laying masses of eggs wherever they land.

Damage

Curling leaves, yellowing foliage, poor growth, and the formation of galls. Large colonies of nymphs will produce a cotton-like mass. Damage is often spotted before the bugs are visible.

Treatment

Large-scale damage is rare. Treat sparingly with Neem Oil or Insecticidal Soap.

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.

Leaf miners are a problem in the larval stage of development wher they feed within leaves

Damage

After flies (mother leafminers) lay eggs on plants, larvae hatch and begin to feed in lines resulting in streaks of dead tissue. Feeding lines look as if someone had taken a white marker and drew random swirls on the leaves. Damage is usually minimal on many ornamental perennials. However, damage to vegetables, especially leaft vegetables can be significant.

Treatment

If the problem is substantial, treat with Captain Jacks Dead Bug Brew or Eight.

The adult stage of the four-lined plant bug greenish-yellow with four black stripes on the backside. Nymphs are a bright orangish-red color with black wing pads on their back.

Damage

Four-lined plant bugs feed on a large variety of herbaceous, ornamental, and edible plants in the garden. Damage is noted by large clusters of black spots that form tiny craters in the leaves. Each spot is usually the same size and shape, unlike bacterial or fungal spots that cause damage with varying shape and size. Spots have a brown center instead of being completely black as may occur in fungal infections.

Treatment

Look for damage in late May and early June. Small numbers of these bugs do not necessarily warrant the use of pesticides. However, with severe damage, Captain Jacks Dead Bug Brew is recommended. Additionally, remove damaged plants at the end of the season to remove any eggs that were potentially laid during the lifecycle.

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.

Bacteria are microscopic, single-celled prokaryotic organisms. Bacteria grow in the spaces between cells, rather than within cells themselves, allowing the diverse array of phytopathogenic bacteria in existence to affect plants in equally diverse means, from production of toxins to the injection of proteins that cause cell death, to production of enzymes to break down cells and their cell walls, and more.

Bacteria are spread in many ways including water splash, rain, wind, insects, animals, unsanitary tools, and infected propagation materials. Bacteria are everywhere and can survive on plant surfaces without issue, requiring a wound or natural opening such as stomata or lenticels to enter and infect plant tissue. Warm, moist conditions are favorable for the establishment of a colony.

Symptoms

Bacteria is best diagnosed by disease symptoms, most commonly the presence of bacterial ooze on and within plant tissues. Symptoms generally develop one to three weeks after infection and are important to catch early. Water-soaked interveinal spots on stems, leaves, flowers, and/or fruits with chlorotic yellow halos that turn brown and necrotic and may coalesce into large areas of necrotic tissue.

Handling and Treatment

Cultural practices are important in the prevention and spread of phytopathogenic bacteria. Regular sanitation of hand pruners and other cutting tools as well as careful handling of plant material to prevent surface wounds is helpful in avoiding spread. Overhead watering can cause a hospitable envoronment for bacteria to thrive. Avoid wetting foliage while watering. Water at the base of plant material whenever possile. Application of Copper can be helpful for large-scale prevention and control. Destroy individually affected plants and dispose of in the garbage.

Plants to Watch

Echinacea

Rudbeckia                                                   

Geranium

Salvia

Delphinium

Lavender

Coreopsis
Chrysanthemum

Lilac

Crabapple

Phytoplasma are microscopic, single-celled bacteria with a single cell membrane and no cell wall. Unlike walled bacteria, all known phytoplasmas are insect-transmitted plant pathogens, generally requiring both the insect and plant hosts for dispersal in nature. Insect vectors of phytoplasmas are phloem feeders, mainly leafhoppers (Cicadellidae), planthoppers (Fulgoromoropha), and psyllids (Psyllidae), inoculated with phytoplasmas when feeding on infected plant material. Once infected by an insect vector, plant material may begin to show symptoms of infection as soon as seven days after introduction, however it may take 6 to 24 months depending on the phytoplasma and insect vector. These long incubation periods in both the insect vectors and infected plant materials make treatment of phytoplasmas tremendously difficult, and interruption of the disease cycle challenging. Additionally, due to the number of vector species and their respective feeding ranges, outbreaks are unpredictable.

Symptoms

Phytoplasmas cause a myriad of symptoms in plants, generally interfering with and causing distorted plant growth and development, affecting over 200 plant species.

Signs include

• Witches’ broom, clustered growth of branches and shoots
• Phyllody, where flower parts are replaced with leaf-like growths
• Green coloration of non-green flower parts
• Bolting, growth of elongated stalks
• Reddening of leaves and stems
• Generalized chlorotic (yellow) appearance
• Decline and stunting of plant growth
• Formation of bunchy fibrous secondary roots

Handling and Treatment

Once infected, plant material must be discarded. Immediately discard plant material directly into the large compost dumpster, away from other plants. Keep area free of weeds to avoid overwintering of the phytoplasma. Insecticide application for insect vectors is an option but is not very effective.

Plants to Watch

Echinacea

Aster

Chrysanthemum and Leucanthemum

Coreopsis

Plant pathogenic viruses are obligate intracellular parasites, requiring a living host cell to grow, where they utilize mechanisms of infected host cells to multiply and colonize plant tissues. Due to the rigid cell walls, viruses, like bacteria, require a wound for entry into the plant tissue or can also be spread by insect vectors, namely sap-feeding insects including leafhoppers, aphids, and whitefly. Viruses potentially encountered in perennials in our area include Hosta Virus X, Cucumber Mosaic Virus, Tobacco Rattle Virus, and Tobacco Ringspot Virus.

Symptoms

• Highly variable depending on pathogen and host
• Mosaic leaf patterning
• Crinkled leaves
• Decline and stunting of plant growth

Handling and Treatment

Wear disposable nitrile gloves when handling plant material and avoid touching any other plants. Wash hands immediately after handling infected material. Remove infected plants, throw away immediately in the dumpster including pots—do NOT compost. Keep growing areas free of weeds to avoid providing additional hosts for virus to spread. Careful handling of plant material to prevent surface wounds for entry.

Plants to Watch

Astilbe

Spirea

Hosta

Roses

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

Downy mildew is a fungal disease caused by a grouping of similar, mostly specialist fungal pathogens that affect a wide variety of plants. Downy mildew is of particular interest in early spring, thriving in cool (between 50F and 75F) and humid conditions, though it may occur at any time throughout the season. Downy mildew overwinters on infected plants and debris as either mycelium or specialized overwintering structures.

Signs

Downy white or gray growths on the undersides of leaves.

Symptoms

• Yellow, translucent lesions on affected leaves, eventually becoming angular and necrotic
• White or gray downy growth on the undersides of leaves
• Sudden leaf drop.
• Symptoms can vary widely due to large range of host and pathogen species

Handling and Treatment

• Remove any affected leaves if early signs of infection are detected
• At or before signs of early disease development, fungicide application may help reduce disease spread, but is difficult to treat
• 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

Plants to Watch

Peony

Roses

Polygonatum

Rudbeckia

Echinacea

Coreopsis

Rust is a fungal disease caused by a diverse group of specialist fungi with complex lifecycles involving up to five spore types and sometimes multiple host plants, requiring a film of water on the leaf surface for spore germination and infection. Each species of rust fungi can infect only a limited number of plants, from just one species to an entire family of plants. Some also have an alternate host where half of the disease lifecycle is on one host plant, and half of their life cycle is on another host plant.  Rusts are easily spread by wind and water, beginning infection when a spore meets the moist leaf surface, causing small yellow translucent lesions to form. While rust infections are rarely fatal, the orange pustules can be quite unsightly and in severe cases can impact plant growth and vigor. Rust infections can return from year to year.

Signs

Yellow, orange, red, or brown pustules on the undersides of leaves. Dark brown or black dots on the undersides of leaves in late summer or early fall.

Symptoms

• Chlorotic, yellow, translucent spots or streaks on upper leaf surfaces, can coalesce and become necrotic
• Yellowing leaves
• Leaf drop
• Leaf distortion

Handling and Treatment

• Remove any 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.
• Keep fence line as free of ditch lilies as possible to avoid providing additional hosts for disease spread
• Treat with Copper Fungicide or Revitalize at or before signs of early disease development

Plants to Watch

Hemerocallis

Alcea

Aster

Chrysanthemum

Crabapple

Lilies

Grasses

Roses

Viburnum

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!