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Pest and Diseases

April 17th, 2010
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Pests of the month (April)

They are out there now, just got to find them. Thought I shall document the pests I found while gardening in the London area. I have highlighted the plants where I found them in bold. The ones I found this month, most can be controlled by using a systemic insecticide, eg. Provado Ultimate Bug Killer. Systemic insecticides are excellent, as they are absorbed into the plant thus only target the pests that consumes our precious plants leaving the beneficial insects unharmed.

Red Lily Beetle (Lilioceris lilii) – They feed on the leaves of spring bulbs like Fritillaries. If left, they may kill the plant or weaken it enough so it will not flower the following year. To control Red Lily Beetle, first pick off the ones you can see and then use a systemic insecticide to finish the job.

Red Lily Beetle

Red Lily Beetle

Rosemary Leaf Beetle (Chrysolina americana) – Shiny green metallic beetles can be seen nesting in the branches of rosemary and lavendar bushes. Extensive damage to the leaves. To control Rosemary Leaf Beetle, carefully pick them off the plant by hand. Do not use systemic insecticide if Rosemary is intended to be used for cooking.

Rosemary Leaf Beetle

Rosemary Leaf Beetle

Scale insect (Coccidae) – Hardly noticable, I was only alerted by numerious ants crawing on an Acer palmatum disectum. The ants were attracted to the honeydew secreted by the pest, they seldom kill their host plant but may make it look yellow and drawn. To control the pest, not for the squeamish … squish with finger tips and use a systemic insecticide to finish the job.

Scale Insect

Scale Insect

Aphid – One week after I removed the scale insects from the Acer palmatum disectum, their cousins, both from the family Hemiptera Sternorrhyncha, aphids arrived. Another sap sucker, that can cause infections to plants if not controlled. Interestingly, there is an Acer palmatum purpurem nearby but is not infected by both pests.

The aphids were probably “put there” by the ants to replace the scale insects. The ants also defend the aphids from their natural predators like ladybirds. To control the problem, used an ant powder for the ants and soapy water for the aphids.

Aphid

Aphid

Powdery Mildew – This was discovered on an Acanthus Mollis and it is a fungal disease. Cause by bad air circulation and plants that are weakened by draught are most susceptable.

Remove and discard all infected leaves; ie. do not compose. This will improve air flow around the plant and reduce its water requirement. When watering, avoid getting the leaves wet.

Powdery Mildew

Powdery Mildew

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