Earwig Damage on Clematis

                      Pest and Life Cycle – (Forficula auricularia) European Earwig overwinters as pairs in the soil (just below the surface) and emerge in spring with the warmer weather. The female lays eggs (up to 60) at this time in shallow soil, with the young adults entering the garden from July to August. The live for about 1 year from hatching and are nocturnal in nature, feeding at night. It should be noted that earwigs are considered beneficial insects as they help to breakdown organic matter and feed on pests such as aphids and slug eggs.

Symptoms – Earwigs feed on rotting organic matter, tender shoots, leaves and blossoms. Symptoms on Clematis appear in midsummer as holes in foliage, flower buds and open flowers, with the stamens often being targeted. The damage is usually worse when they are grown on trees or through shrubbery (the one shown was grown on a rhododendron).

Management – You can minimize future damage by spraying the affected foliage with an insecticidal soap or pyrethrin based product (Trounce) at label rate (this acts as a deterrent) or by applying diatomaceous earth in and around the vine. Simple traps made of rolled newspaper or cardboard can also be placed on the ground near the affected plant. These will attract the earwigs as a daytime nesting site and you can simply tip the lodged earwigs into a bucket of soapy water and return the trap to the ground. This method should reduce the earwig numbers in the immediate vicinity.

Prevention – 1. If possible, cultivate the soil (in spring and fall) around the damaged plants to disrupt overwintering adults and expose newly laid eggs, which will dry out. 2. Keep areas prone to damage clear of garden debris such as leaf litter or stacked wood, as both of these are good earwig habitat.

Grape Leaf Blister Mite / Erineum Mite

Pest and Life Cycle – (Colomerus vitis) Erineum Mite is a pest that produces bumps or galls on the upper surfaces of grape leaves. They overwinter in the bud scales and migrate to developing shoots and leaves in early summer. By late summer to early fall the mites return to the buds to overwinter. There are multiple generations per year.

Symptoms – Leaves develop gall-like blisters (these are reddish at first, maturing to green) while on the reverse white hairs appear on the indentations – the latter is often mistaken for downy mildew.

Management – For minor infestations simply remove and destroy (burn or put in garbage) the affected leaves. Serious infestations are only likely to adversely affect young or juvenile vines. Sulfur-based pesticides (at label rate) can be used when severe outbreaks occur, but these are most effective in the early season, just as the galls are forming. Please note that sulfur cannot be used on sensitive grapes such as ‘Foch’, ‘DeChaunac’, ‘Concord’ or any Vitis labrusca variety. Summer Oils or Insecticidal Soap-based products can also be used (at label rate), but these will reduce beneficial insects.

Prevention – 1. Carefully inspect new vine purchases for any symptoms of mite infestation. 2. Pick-up the leaves of infected vines in the fall and discard in garbage or burn – do not home compost them. 3. Avoid spraying herbicides around grapes as these also harm natural predatory mites.

Powdery Mildew on Norway Maple

Pest and Life Cycle – (Sawadaea bicornis or Sawadaea tulasnei) Powdery Mildew is a fungal disease that overwinters on the fallen leaves and live buds of infected Norway Maple (Acer platanoides) trees. A combination of high humidity and drought stress favours this disease, with symptoms being quite visible by midsummer in coastal British Columbia – although in other parts of the country they may appear much later.

Symptoms – Leaves develop powdery white patches beginning on the upper surface and can eventually cover the entire leaf. Badly infected foliage turns yellow and may drop prematurely. The lower part of the crown is usually more adversely affected.

Management – Pick up and discard (put in garbage or burn) any fallen leaves – do not compost at home. Deep water affected trees during periods of summer drought. Fungicides or chemical controls are unnecessary as this disease is superficial and rarely causes long-term damage to established trees.

Prevention – 1. Avoid planting susceptible cultivars such as ‘Crimson King’ and ‘Schwedleri’. 2. If you live near a green belt where Bigleaf Maple (Acer macrophyllum) grows, consider not planting Norway Maple. Bigleaf Maple is also affected by powdery mildew (Sawadaea bicornis) and this disease may constantly transfer to adjacent Norway Maples. 3. Plant Norway Maples in open areas with good air circulation and sun exposure, allowing enough room for the ultimate height and spread. 4. Do a little selective pruning of the crown to improve air circulation. 5. Rake-up and discard (in garbage or by burning) infected leaves in the fall – do not put them in the home compost. 6. Keep existing trees healthy and less disease prone by deep watering during dry spells and avoiding soil disturbance in the root zone.

Photinia Leaf Spot

Pest and Life Cycle – (Entomosporium maculatum or Entomosporium mespili) Photinia Leaf Spot is a fungal disease that overwinters on infected leaves and twigs, releasing spores during both spring and fall rains. These are dispersed by wind and water droplets, infecting the new foliage. This disease also affects Rhaphiolepsis or Indian Hawthorn and several other members of the rose family.

Symptoms – Bright red to maroon spots appear on both leaf surfaces (upper and lower) of newly emerging or young leaves. The spots often spread and merge, causing leaf defoliation. Older spots have ashen or brown centers with a distinct burgundy-red halo.

Management – Preventative sprays (see below) are your most effective management tool, although fallen leaf litter should be removed (thrown in garbage) or destroyed (burned), but not composted. Dead or diseased branches should also be pruned out once the wet weather has subsided.

Prevention – 1. If this disease is persistent in your area spray with a copper-based fungicide (at label rate) every 10-14 days from bud-break, up to the point when the new leaves have matured. Another preventative spray may have to be applied in late summer or early autumn, before the rains begin again. 2. Always carefully inspect new Photinia purchases for any signs of spotting. 3. Avoid irrigation practices which keep the foliage wet, as this promotes leaf spot. 4. Do not over-fertilize to try to compensate for leaf loss, as this only creates lush foliage which is more susceptible to infection. 5. Severely diseased specimens may have to be removed and if it is being used as hedging, consider replacing with another broadleaf evergreen such as English Laurel (Prunus laurocerasus), as it is less prone to defoliation in coastal British Columbia.

Aphids on Branch Tips

Pest and Life Cycle – There are usually two different pests involved with this problem – that being aphids and ants. Some species of ants literally farm aphids, raising eggs and carrying newly hatched aphids to host plants which usually includes members of the Prunus genus such as cherries and plums (although Pyrus or pear is shown here). The aphids suck the juices from the new leaves and secrete a sugar-rich honeydew, which is a food staple used by the ants. These clusters will appear whenever the ants are active, usually late spring through to fall.

Symptoms – Heavy clusters of aphid colonies (these may vary in colour from green to reddish, or even black) can be seen on the branch tips of infected trees. Many of the terminal leaves will curl due to the aphids feeding and gatherer ants will be present. Superficial sooty mold may also be seen, growing on the secreted honeydew.

Management – Both pests will need to be controlled with the best solution for the ants being a barrier band (see below). Badly infested tips can be pruned off or the aphids can be dislodged by simply using a hard spray of water from the hose. A low impact pesticide such as Trounce (a combination of insecticidal soap and Pyrethrin) can also be used at label rate as a spray. Larger trees and infestations can be handled by releasing a natural predator such as ladybugs – these will remain on the tree as long as there are aphids to eat. Please note that Trounce is a non-selective pesticide and cannot be used in combination with the ladybugs, as it will kill both beneficial and pest species.

Prevention – The best prevention is to control the ants by placing a sticky barrier on the trunk to prevent the ants from accessing the tree. Tanglefoot is a good organic product to use as it is made from non-drying natural gum resins. The band should be placed on the trunk in early spring before the ants become active, start by putting a protective backing on the trunk (pre-coated bands are also available) such as shrink wrap held in place by duct tape. It is important that there are no gaps behind this that the ants can get through, so for trees with furrowed bark use a piece of 6-8″ wide fiberglass insulation covered in shrink wrap. Spread at least a 3″ wide layer of Tanglefoot paste over this band and stir occasionally to ensure that it isn’t breached by debris or dead ants. Please note that this control is only effective if there are no other access routes to the tree. The band can be removed in autumn when the ants are no longer active.

Apple Scab

Pest and Life Cycle – (Venturia inaequalis) Apple Scab is a fungus that affects both fruiting apples and ornamental crabapples – it is quite common in areas prone to wet springs, such as coastal British Columbia. The fungi overwinters in infected leaf litter, with new spores being produced as the young leaves emerge on the tree. These are carried by wind and water droplets, germinating on moist foliage.

Symptoms – The leaves develop rounded or irregular spots which may appear olive green, brown or black in colour. Fruit produces symptoms of brown to black scabs, with corky lesions and cracking being common with severe infections.

Management – Sulphur or copper-based fungicides (follow label rate) may provide some control, but these will have to be sprayed weekly throughout the rainy season from spring to early summer, which is not always practical for the home garden. Rake-up and dispose of (in garbage or by burning) fallen leaves in autumn – do not compost them.

Prevention – 1. The best way to minimize this disease is to choose scab resistant apple cultivars such as ‘Jonafree’, ‘Redfree’, ‘Liberty’, ‘Freedom’ and ‘Prima’ for growing in coastal gardens. For ornamental crabapples choose ‘Louisa’ (weeping form), ‘Red Jewel’ or ‘Prairiefire’. 2. Space newly planted trees adequately to allow for good air circulation. 3. Prune individual trees to allow for good air circulation within the crown. 4. Train apple trees espalier-style and keep under a plastic cover during the wet weather from spring to early summer.

Black Spot on Roses

Pest and Life Cycle – (Diplocarpon rosae)  Black Spot is a fungal disease that overwinters on infected leaves (both those remaining on the plant and on the ground) and stems. Spores are carried to the new foliage through water droplets (rain and irrigation), infecting exposed leaves.

Symptoms – Rounded black spots (with feathery edges and often with yellow margins) appear on the top surface of the leaf. When severe, the spots become quite large or join together, with the infected leaf eventually turning yellow and dropping – sometimes causing complete defoliation. It is most prevalent in warm weather with prolonged rains or overhead irrigation.

Management – Carefully monitor roses as the new leaves emerge and immediately remove affected foliage. Dispose of in the garbage or by burning, do not compost. Spray with a sulphur-based or fixed copper fungicide (read label for rate and timing) through the remaining wet weather.

Prevention – 1. Replace badly affected roses with disease resistant cultivars such as ‘Julia Child’, ‘Livin’ Easy’ (‘Fellowship’), ‘Playboy’, ‘Bonica’ and most Rosa rugosa hybrids. 2. Avoid overhead watering whenever possible, keeping irrigation to the soil level. Water only in the morning so that dampened foliage dries quickly. 3. Grows roses in a full sun exposure with good air circulation. 4. Always remove plant debris (fallen leaves, pruned branches) from around roses and dispose of in the garbage (or burn). Do not compost them. 5. Mulch roses in spring to cover overwintering fungal spores. 6. Use lime-sulphur as a dormant spray before bud break in spring to kill overwintering spores. 7. Remove any diseased stems in fall and hard prune in spring (when the Forsythia begins to bloom) in order to remove old wood and create stronger new branches.

Azalea Leaf Gall

Pest and Life Cycle (Exobasidium vaccinii) – Azalea Leaf gall is a fungal disease that affects both azaleas and rhododendrons (also Leucothoe, Camellia sasanqua and blueberries). It overwinters on the bark and bud scales of host plants, infecting the new foliage as the buds open in spring. The spores are generally spread by rain or irrigation water.

Symptoms – The fungus primarily affects the foliage (occasionally flowers and buds), with infected leaves becoming quite distorted or fleshy (some might describe it as waxy). These turn whitish to pale green, or even pink-tinted – becoming brownish with age. They eventually harden and drop to the ground.

Management – Monitor your azaleas carefully in spring and remove any galls as soon as they form. Dispose of in garbage or by burning – do not compost.

Prevention – 1. Avoid overhead watering if possible. Water in the morning so that the foliage is dry by afternoon. Do not water in the evening as this keeps the foliage damp for extended periods of time which promotes this disease. 2. Avoid planting susceptible azalea cultivars such as ‘Gumpo White’, ‘Mother’s Day’ and ‘Rosebud’. 3. Replace or replenish the mulch below infected plants in order to cover any residual spores. 4. Space your azalea plants to allow for better air circulation and avoid mass planting. 5. Spray with a fixed copper (at label rate) just before bud break in spring and reapply 2-3 weeks later. This will put a protective coating on the foliage.

Peach Leaf Curl

Pest and Life Cycle – (Taphrina deformans) Peach Leaf Curl is a fungal disease that is more prevalent or severe in regions with cool weather and prolonged, wet springs. The spores overwinter on the branches and bark, as well as leaf litter below infected trees and germinates in spring when the buds swell – infecting the newly emerging leaves. This disease affects both peaches and nectarines.

Symptoms – The leaves curl and become thickened or distorted, also turning reddish – these eventually become a greyish-white and drop. Fruit and flowers often abort with severe infections and branches may suffer tip dieback.

Management – Monitor carefully in spring and remove all affected leaves as soon as symptoms appear, discarding them in the garbage (do not compost). Rake-up and dispose of fallen leaves and prune out any twig dieback.

Prevention – 1. Plant disease resistant cultivars – with the best currently being ‘Frost’, other good choices include ‘Redhaven’, ‘Pacific Gold’ or ‘Renton’. Another option is to grow a genetic dwarf peach (‘Bonanza’, ‘Empress’) in a large container that can be rolled undercover or temporarily protected with a beach umbrella during the wet spring weather. 2. Train your peach trees espalier-style under the eave of a building (which protects it from the rain) on a south or west-facing wall. Alternatively, you can erect a temporary plastic covering to keep your foliage dry during wet springs. 3. Always dormant spray or apply fixed copper before bud break to kill overwintering fungal spores. Copper sprays can also be applied (at label rate) after harvest in September. 4. Foliar sprays of seaweed or kelp-based fertilizers during the growing season have been shown to reduce the severity of this disease.

Heuchera Rust

Pest and Life Cycle – (Puccinia heucherae) Heuchera rust is a fungal infection which prefers warm, humid conditions and poor air circulation. Spores are produced on the lower side of the leaf and dispersed by wind or water droplets, infecting new foliage.

Symptoms – The upper surface of the leaf develops subtle pock marks (which can contrast the leaf colour, depending on the cultivar) while the reverse produces golden-yellow to brown raised rust pustules. Heavily infected leaves may become distorted.

Management – 1. Check your plants frequently for symptoms of rust. 2. Completely remove the foliage of all rust-infected plants, being careful not to cut the growing point or terminal. 3. Dispose of infected leaves by burning or throwing into the garbage – do not compost. 4. Consider replacing the soil (about a 1/2″ depth) on the surface immediately below the crown of the affected plant. 5. Spray with a copper-based fungicide (at label rate) approved for domestic use in your growing area. 6. Always clean your pruning tools and wash your hands after handling an infected plant.

Prevention – 1. Quite often the disease is introduced to the home garden through infected plant stock, so inspect your new Heuchera purchases carefully. 2. Water Heucheras in the morning so that the foliage is dry by the afternoon. Avoid watering in the evening as this creates humid conditions that are ideal for rust. 3. Don’t create a monoculture with mass plantings of Heuchera, spread them out instead and space with non-host plants (avoid Saxifraga, which is also a host to this rust species). 4. Clean out older tatty foliage in spring as the new leaves emerge. 5. Golden, peach and orange-leaved Heucheras seem to be more prone to infection while some older strains, such as ‘Palace Purple’, are quite resistant.