Hi (first my posting btw). I specialize in these little microbes and their networks. Neem oil will harm some of the beneficial microbes in the soil and some that even live on the foliage as well. Others however, can benifit from it given the concentration of the active ingingredient in the oil and the emulsifier that is blended to help it mix with water. The majority of neem are faty acids omega 3, 6,&9; many benificial microbes eat these. And unless you are Spryaing the neem oil directly on or below the soil, small ammounts should barely drip on the ground. It never hurts to replenish the microbial population with compost tea or a little molasses and fish emulsion. Hope this helped. This post was edited by ExteriorCareService on Tue, Aug 6, 13 at 13:28

Whitish specks on the upper surface of leaves and dark spots varnish-like on the bottom are symptoms of Rhododendron Lace Bugs, Stephanitis rhododendri, and Azalea Lace Bugs, Stephanitis pyrioides, small insects with transparent wings on under-surface of leaves.. This insect hatches early in spring as the new foliage begins to mature and its numbers may build to damaging levels with successive generations. Lace bugs reach their peak in late summer and do their worst in sunny, exposed sites. Spiders are important predators of lace bugs and since they shy away from sunny, hot places, plant your azaleas where there is some shade. Insecticidal soap, horticultural oil, or a systemic insecticide may spare your azaleas the damage if applied in spring when the first hatchlings are noticed. Care must be taken to spray the lower surfaces of the leaves where the lace bugs live. Moving a plant to an area with more shade may alleviate the problem. Lace bugs are more prevalent on certain varieties. The following azalea cultivars have resistance to azalea lace bug: Dawn, Pink Star, Ereka, Cavalier, Pink Fancy, Dram, Seigei, Macrantha, Salmon Pink, Elsie Lee, Red Wing, Sunglow and Marilee. Rhododendron Lace Bugs, Stephanitis rhododendri, and Azalea Lace Bugs, Stephanitis pyrioides adults are about 1/8-inch long. The body is pale yellow. The lacy wings (very distinctive) are held flat over the back and are transparent with two dark spots present. The nymphs are black, spiny and smaller than the adults. The eggs overwinter partially embedded in leaf tissue. The eggs hatch in May. The nymphs mature into adults in June and lay eggs during late June and July. The second generation of nymphs appears in August. The overwintering eggs will be laid when these nymphs become adults. Lacebug adults and nymphs feed on the undersides of leaves by piercing the leaves with their mouthparts and sucking the plant juices. This causes a mottled, silvery or white discoloration, known as stippling, on top of the leaf where the chlorophyll has been removed. The undersides of leaves are covered with dark brown to black, sticky spots of excrement. Plant rhododendrons in shade to maximize the activities of beneficial insects. Varieties that are attacked by lacebug will recover if moved to shadier areas. They only get lacebugs in full sun. The National Arboretum warns: "Excess nutrients (fertilizer) may promote larger than normal populations of azalea pests like lace bugs Thrips, Thrips imaginis: This insect is a seasonal pest, causing most damage in mid to late summer. Signs of damage include silvering of the foliage and distortion of growing points and flower buds. The underside of leaves may be covered with excreta of the insect, which are like brown tar droplets. There are no effective specific biological controls and thus control can be difficult to achieve. Thrips are preyed upon by ladybirds and lacewings but these predators cannot control thrips in plague situations.

kquat, Horticultural oil is the broad term to include oils that are sprayed on plants and trees no matter what time of year it's used. There is a difference in the sprays that are used after the bud begins to emerge in the spring and the oil sprays that are used when a tree goes dormant. The insect has to be covered with the oil to do any good, and the oil does not remain on the tree as a protectant. I believe that a label would precaution using an oil on a tree if freezing temperatures are a possibilty. You know not to spray oil on your trees if the temperatures will get to 80 degrees F. I mixed canola oil with water and soap on some trees (including citrus)and even though it was in the cool of the morning, the temperatures went up and one of my citrus ended up loosing all its leaves. I only sprayed the one that had Cottony Cushion scale on it. The leaves grew back and the tree was prettier than ever. Maybe I should do that to all my trees -- think? At least the Leafminers would take off. Neem oil is not the same at all. Brass

Kimm, you are mistaken about the bad health of plants being an issue for why pests invade. Grubs never attack a poor lawn....why would they, there's nothing there for them to eat. What the grub wants is a good healthy rooted lawn that will feed them until the cows come home. Same for houseplants; they want the good stuff, the green, healthy leaves and stems where there's lots of juices to suck and eat of the foliage. True, the more healthy a plant, better it can stand up to adversity....same goes for a lawn. But when looking for bugs, they, like us, only dine where the food is good and plentiful. Bugs when they are in numbers, can cause harm to a plant, can cause stunted growth, loss of bloom, otherwise wilting plants that do not live very long. "water is an insecticide"! Where did that come? I think you mean if you blast a stream of water at a bug, he loses his grip and so falls out of the plant...and in so doing, cant harm the plant. Yeah, I guess that counts for something too. Many garden centres have on their shelves an insecticide that is safe for most houseplants. The label might identify the contents as being "for houseplants". In so identifying, the contents will treat what is commonly the pests that are found on all our houseplants. aphids, whiteflies, scale, thrips, mealybugs, spider mites and so on. Other product labels might identify one pest in particular that it treats. But the very best ridder --you cant beat it---is on the ends of your hands. Pick a bug up and squeeze it between thumb and forefinger. He'll never again eat at your plant. I guarantee it. Now its his children that is the problem. They should be given the loving hug as well.