"Phrederik" wrote:

Can anyone suggest some simple questions to ask at a garden center to really
see if the person you are talking to knows what they are doing?

1) "Is Sevin good for controlling spider mites on spruce and juniper?"

The answer is no, it makes the problem worse. Do not use carbaryl
(Sevin) or cyfluthrin (Tempo 2) as these stimulate mite egg-laying! One
reason that spider mites become problems in yards and gardens is the use
of insecticides that destroy their natural enemies. For example,
carbaryl (Sevin) devastates most spider mite natural enemies and can
greatly contribute to spider mite outbreaks. Malathion can aggravate
some spider mite problems, despite being advertised frequently as
effective for mite control. Soil applications of the systemic
insecticide imidacloprid (Merit, Marathon) have also contributed to some
spider mite outbreaks.

2) "Are botanical insecticides made from natural products toxic to pests
but harmless to other living things?"

No. Nothing could be further from the truth.* Plant-derived poisons are
only sometimes less toxic to man than synthetic agrichemicals.
Rotenone, from the roots of derris plants, is toxic if swallowed or
inhaled.* Both pyrethrum and rotenone are low in toxicity to mammals yet
highly toxic to fish. The yardstick for comparing acute, short-term
toxicity is the LD50 or lethal dosage needed to kill fifty percent of a
group of test animals (rats, rabbits, etc.).* When you compare LD50
figures, the chemical insecticides malathion and sevin rank safer than
nicotine sulfate, a botanical poison derived from tobacco.

3) "Is fall the best season for pruning?"

No. This is false for several reasons.* Shrubs and trees store
carbohydrates (food materials) in their branches and leaves, so fall
pruning can reduce their cold hardiness.
Azaleas and other spring-flowering plants would bloom poorly if pruned
in fall, as next year's flower buds are present at that time.* Such
plants are best pruned in spring right after petals fall.

4) "Do mushrooms and toadstools sprouting in your lawn mean that the
soil is deficient in nutrients?"

No. In actuality, these plants are merely the above-ground growth of
fungus organisms living in soil.* Some fungi live on buried lumber, dead
roots, or fine particles of organic matter.* Others live in harmony with
tree roots, assisting in the uptake of water and nutrients.* A few cause
plant disease. The sudden appearance of mushrooms does not mean the lawn
needs lime, fertilizer of anything else.*If you object to their
sprouting in lawns or gardens, use a rake to dispose of them.* There is
no chemical control for mushrooms.

--
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