I am wondering about neonicotinoids [pesticides]. I know their effects can last several years in woody plants, but what about, say, perennials? I heard something about being careful.
You may be referring to the 2013 incident in Oregon when a neonicotinoid sprayed on flowering linden trees killed at least 25,000 bumblebees along with tens of thousands of other bees, ladybugs and other insects. Ironically, it happened during National Pollinator Week.
The neonicotinoid class of pesticides is systemic, spreading throughout plants — including roots and pollen — which has implicated it as one factor in the country's pollination crisis. That said, consult product labels and contact manufacturers for more specific information. This is a critical topic today and research is ongoing. Meanwhile, avoid spraying these products, which contain ingredients such as imidacloprid, clothianidinor dinotefuran, directly on flowering plants (including weeds). Also, if using a granular formulation, avoid the roots of nearby flowering plants that can absorb the insecticide.
Is it a problem to grow black raspberries near red raspberries? Are the wild wineberries in my woods likely to cause a disease problem for the raspberries?
Black raspberry plants are very susceptible to raspberry mosaic virus, which can be a minor problem for red raspberries. It's OK to plant them near each other, provided they are disease-free plants. Also, remove any wild brambles (including blackberries and raspberries), because they can carry disease such as rust or phytophthora. Wineberries are not a disease problem, but they have escaped cultivation in Maryland and other states, spread rampantly and are now recognized as a non-native invasive plant harmful to the environment. Remove them as soon as possible.
Plant of the week
Apple
Malus domestica
Who can resist the image of picking plump juicy apples in your backyard? Apples are the quintessential American fruit. Spring blossoms cover the trees, which produce for decades. But for good fruit, do your homework before planting. Start with a suitable site — full sun is a must — and choose the variety wisely. Success requires high resistance to apple scab, cedar apple rust, powdery mildew and fireblight. Usually fruit trees are shipped bare root (with the roots exposed). Choose from hundreds of cultivars — most need a pollinizer; some need specific ones. Plan on regular pruning and feeding. Find apple-growing basics and recommended varieties on the HGIC website.
—Ellen Nibali