Category Archives: pests

methods for controlling pests

Rhododendrons and other Poisonous Plants

My fascination with poisonous plants was piqued recently while researching organic methods for eliminating rhododendron root weevils. You’ve probably seen their damage-scalloped or notched leaf margins starting in May or June. The adult weevils feed at night but usually do not seriously injure the plant. It’s the larvae feeding unseen on roots that will cause severe damage and death of the plant if weevils are left uncontrolled.

Because rhododendrons contain toxic resins that are more concentrated in the foliage, to pesticides along with a tolerance for the toxins in the leaves. Organic or even chemical sprays have little effect anymore according to a study funded by the Rhododendron Society of America and end up killing hundreds more predatory beetles and other beneficial insects in the process.

Applying parasitic nematodes to your soil is one way to control weevils. Other tactics include placing a shallow pan of water under the plant or a soup can filled with soapy water buried up to the to attract and drown the adults . You can also try banding the trunks with tape or waterproof paper and smearing the bands with a sticky barrier like Tanglefoot. Spreading some coffee grounds under the plants also helps to discourage them from crawling up the trunk after they spend the night at the base of the plant. And if you’re really determined you can hand pick them after dark- effective but not much fun.

Rhododendrons are just one or our beautiful plants that are poisonous. Children are more susceptible to the effects of plant toxins and should be taught not to eat seeds, berries or leaves from any plant. Do not assume a plant is nontoxic because birds or wildlife can consume it without harmful effects. Be prepared for an emergency by keeping syrup of ipecac on hand and the number of the Poison Control Center. ( 1-800-222-1222 )

Small pets can also be at risk if they ingest parts of poisonous plants out in the yard. Know what plants you have and keep a list. Oleander and foxglove are notorious deadly plants. Here are just some others you might not know.

Hydrangea leaves, flowers and branches contain cyanide. Lantana foliage and especially unripe berries also contain dangerous toxins while delphinium leaves and seeds contain toxic alkaloids which decrease as the plant ages. Sweet peas, lobelia, impatiens, carnations, calla lily, mums and bleeding hearts also have plant parts with come degree of negative effect if ingested.

Surprisingly, even some vegetables contain natural toxins. Diseased celery and green potatoes as well as potato leaves and sprouts produce a very strong toxin. Raw, green, young asparagus shoots can cause dermatitis and the red berries that form on their feathery branches are poisonous. Large quantities of tomato leaves and stems contain alkaloid poisons. Livestock have died from eating the foliage. I guess the deer that browse your tomato vines aren’t ingesting enough to cause them harm as they seem to know just when you have another set of buds for them to nibble.

Trees are not the most common cause of accidental poisonings around the home but a few species may present a hazard.
 
The black seed inside apples contain cyanide although you have to eat large quantities for them to be deadly. Peach kernals, bark and twigs contain cyanide also as do apricot, cherry and plum pits.

You don’t have to eliminate plants around the home that have natural toxins. Humans have lived for centuries around gardens and orchards. Just be prepared by knowing what plants grow on your property.

Tobacco bud worm and you

petunias

Geranium, penstemons and petunias sometimes become infested by budworms.  Foliage may be chewed, flowers may open tattered and full of holes or appear dried up and not open at all.   Tiny black droppings on the foliage are left behind. The striped caterpillar larval form of a native moth is a close relative of the corn ear worm, the tobacco or geranium budworm.  Moths lay eggs singly on host plants.  After hatching, the caterpillars chew fully opened flowers and occasionally dine on the leaves.  Spraying early on with organic BT is effective if done before the worms burrow inside the flower buds.  Remove dried up buds and flowers that may harbor the caterpillars and pull up and destroy ragged, end-of-season petunias that my have eggs sticking to the plant remains.  There may be two generations per year so preventative spraying with BT may protect established plants of geraniums or penstemon.  

Fuchsias

If your fuchsias aren’t blooming and the leaf tips look curled up and deformed, your plants are infested with fuchsia gall mite.  First discovered on the West Coast in 1980, it is often mistaken for a disease because of the way it distorts and twists fuchsia leaves and flower buds.  The damage caused can be debilitating.  The leaves curl and distort so much that normal photosynthesis is disrupted and weakened plants fail to bloom  Infested plants usually recover if further mite damage is controlled.  Prune off all distorted foliage and buds.  This may be the best method of control as petroleum oil or insecticidal sprays need to be made every 4-7 days to disrupt the mite life cycle.  Neem oil is not recommended for use on fuchsia flowers.

There are several gall mite-resistant fuchsias, both hanging and upright, that are very bit as showy as the traditional fuchsia varieties.  if you have been plagued by fuchsia mites, try growing one of these instead.