As a living organism, plants can get sick from both bacterial and viral diseases. We’re going to give you a brief overview in this week’s gardening tip.

Bacteria are single celled organisms which reproduce asexually by binary fission. There are around 170 species of bacteria that can cause diseases in plants. They enter through wounds or natural openings such as stomata in leaves. Bacteria live and grow in the spaces between cells and are normally present on many plant surfaces. They generally only cause problems when conditions are favourable for their growth and multiplication. This may include humidity, crowding, and lack of air flow

Bacteria is most active in the winter when plants aren’t growing as quickly and are easily stressed. Often transmitted by wind, animals, infected tools, bacterial diseases can include fireblight, crown gall, and bacterial canker.

Viruses are much smaller than bacteria and “live” inside plant cells. Viruses are not so much a living organism, but rather a core of nucleic acids that switch off the host cell’s DNA and use their own nucleic acids to instruct the cell apparatus to reproduce new viruses.

There are only a few viruses that are frequently seen in the garden. They are transmitted often by humans such as through contact by the hands, or gardening equipment like pruners. Insects are another common virus vector especially sap-sucking insects like aphids, thrips, and whiteflies. Few viruses can also pass through infected seed. Viruses are often killed by exposure to heat and sunlight, though some can survive being outside their hose and even the composting process. Commonly seen viruses in the garden include Cauliflower mosaic virus, cucumber mosaic virus, and tobacco mosaic virus.

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