APHIDS are small, soft-bodied insects with piercing and sucking mouthparts. Look for these green, white, wooly or black insects on leaf axils and veins. These critters suck sap from the new growth causing deformities and sometimes galls (bumps). For much of the year, aphids reproduce parthenogenically (without fertilization by males) which leads to rapid population growth. Early control is crucial. Handpick, introduce a predator such as Praying Mantis or Ladybug and as a last resort, apply a natural insecticide.
RUST
SPIDER MITES These are teeny tiny members of the arachnid class and usually identified by the damage they cause, incredibly fine webbing between leaves and stems. Piercing and sucking mouthparts lead to leaf spotting and if left uncontrolled, defoliation will occur. They thrive in a dry environment, so go on the offense with a spray of water. Misting regularly can help prevent an outbreak. When clear water is no longer effective, reach for an insecticide, preferably one with an oil for best control. EMERALD ASH BORER A recent introduction, this pest has no natural predators and is almost unchecked in its establishment. This green jewel-toned beetle is one we need to call in the urban forester or arborist. Treatment is challenging and work is ongoing with Canadian Forest Services, CFIA, US Dept of Agriculture, several layers of government and universities to find solutions to this devastating pest. Look to this model as a reminder that prevention is the best cure. Innoculate ash trees and do not take firewood outside your region to avoid pests travelling! POWDERY MILDEW shows up as a fine grey/ white film over the surface of leaf. More noticeable on Ninebark, Lilac, grapes, squash and beebalm. It will look and feel like it can be rubbed off but the spores remain unless treated. Ultimately, the powdery film blocks the leaf’s access to sunlight, thus weakening the plant.
POWDERY MILDEW
Mmmm... lunch time!
APHIDS
RUST looks like, well rust! A group of fungal diseases get together to harm many different plants (roses, daylily, tomato and grasses). Small dots of rusty orange to brown, yellow and red appear on leaves and get bigger with time. Eventually, the bumps burst open, releasing spores to the wind and water. Most of the common fungal diseases take hold in years where a cool wet spring is followed by a humid summer. Treatment for them is similar: water in the morning at the base of the plant so leaves dry during the day and prune to provide airflow through the leaf canopy. If the battle is ferocious or the season wet, spray or sprinkle garden sulphur on the leaves and soil to reduce the viability of spores. Although these are some of the more common issues affecting our plants, there are certainly more, however, a mind for prevention and overall vigilance will reduce the devastating effects. As always, if a problem is beyond your comfort level to diagnose, bring a 10-15cm sample (in a sealed bag) of the affected plant along with the suspected offending organism to your local independent garden centre for an expert diagnosis!
SPRING 2020 • 13
