Q. Two years ago, you correctly diagnosed our tomato plants with spider mites from pictures we sent. Last year we got spider mites again. We started most of our tomatoes from seed last year but bought a few plants from a local nursery and planted them in each of the vegetable beds. Is it common to get spider mites from nursery plants?  A. I don’t know how common it is for pests to be brought in from plant nurseries but I know it is more common than I would like. I have personally witnessed and identified disease and insect problems coming from nursery plants (houseplants, transplants, fruit trees and landscape container plants) before they were planted. Some disease problems on locally purchased container fruit trees. Sometimes insects and diseases can be problems when purchasing nursery materials. This disease infection may have started in the wholesale nursery first and passed on to the local consumer by the retail nursery.Avoid buying problem plants and introducing them into your home garden or landscape.             Some plant problems are easy to see and others are not and don’t develop fully until later. Growing plants free of insect and disease problems requires knowledge about the pests, a clean growing area and a regular prevention and treatment program. Off-color leaves and spotting of leaves can be indicators that they are not healthy or they were poorly cared for. Purchasing nursery transplants can sometimes bring problems into the garden. It can be a problem when low prices are an expectation by the nursery or garden center which may encourage a lack of care or over application of pesticides by the greenhouse producer. Inspect your plants before purchasing and avoid buying those with problems at the get-go.             If possible, put plants in isolated areas until you are sure they are “clean”. This is a common recommendation when buying houseplants. Houseplants are frequently loaded with disease and insect problems and infest other plants once inside the house. Fireblight disease was brought into this planting of apples and pears by introducing an infected Bartlett pear tree from a retail nursery. Once established, this disease spread to other European and Asian pears causing a lot of destruction and loss of plant life.             When bringing home plants, spray them with oils and soap and water sprays before planting. Don’t bring home “bargain bin” or dumpster plants thinking you’ve got a deal. You are asking for trouble unless you know what you’re doing. Don’t risk contaminating pristine plants by mixing them with plants unknown to you.If you must do it, keep them isolated from other plants until you are sure they are healthy.             As far as spider mites on tomatoes are concerned, inspect plants using the “white paper method” and a hand lens. Remove weeds growing in the containers, remove dying or damaged leaves, spray plants with soap sprays, and alternate with neem and other oils when you see them. Inspect plants