If you're a gardener, one time-tested tradition for getting through the cold days and long nights of winter is planning next year's garden, complete with poring over seed catalogs and searching for that perfect plant. The internet has given us the ability to order almost anything from anywhere. While this greatly expands the types of plants available to the home grower, please consider the source of your plants before clicking the "Buy Now!" button.
Commercial producers and nurseries are inspected by state agents to look for insects and diseases. Seeds, whole plants, and plant parts (tubers, bulbs, cuttings, etc.) that are sold by large commercial companies are usually either treated, or are grown in areas with low pest pressure. Individuals that sell seeds and other plant parts via the internet, or plants acquired through local plant shares, are not subjected to this scrutiny. No one is inspecting the plants before they're shipped to ensure their health. More disturbingly, they may not be inspected at national or state borders. Last year I purchased castor bean seeds from China to see what would happen. They arrived a few weeks later. There was a customs form attached to them, identifying the contents as "craft supplies." I don't know if the seeds were inspected at customs, but there was nothing to indicate that they had been (I autoclaved the seeds just to be on the safe side).
A few days ago I decided to peruse a few online sources of plants. Quite frankly, I'm concerned. Popular sites such as eBay, Etsy, and Dave's Garden (and these are only a few among many) contain numerous opportunities to acquire new plants … and possibly new pests. Here are a few examples:
Yacon tubers shipped from Lisbon, Portugal
Soil is a great way to transport insect eggs, nematodes, fungi, and more. Anytime I see an underground structure (bulb, tuber, corm, roots) being offered for sale, I worry. Even if they're washed and scrubbed really well, they can still transport plant pests inside them or on their surface. I've found tubers and corms for sale from places ranging from Lisbon, Portugal, to Bangkok, Thailand, to Hong Kong. I have no idea what kinds of pests they have in Portugal, Thailand, or Hong Kong, and I frankly have no desire to find out in my backyard.
Centella asiatica seeds for sale from India
Some insects and pathogens are seedborne, meaning they can be carried in or on a seed. The plant pictured above is offered for sale as seeds from India. While there’s no guarantee that the plants pictured are the ones seed was collected from, all the spots I see on the leaves in that picture do concern me. Leaf spots with a dark purple margin and tan center are characteristic symptoms of a few types of pathogenic fungi; two common suspects (Cercospora and Septoria) are known to infect this plant, and both may be seedborne. While we have Cercospora and Septoria fungi in Illinois, they’re probably different species than the ones in India. New species can cause new diseases on new plants; this is something I don’t want happening because of me.