Vine Weevil
The most serious pest in the growing of Begonias is without doubt Vine Weevil. The little blighters are whitish/grey in colour and about one quarter of an inch long. They tunnel into the tuber and sometimes the damage is difficult to see as what they eat is deposited behind them filling in the hole they have made. Unless treated they can destroy the tuber completely. The parent is a long, hard skinned, beetle which lays it's eggs around the stem of the plant in spring where the eggs hatch and another generation of vine weevils do the damage.
The above picture shows a weevil as found feeding inside tubers
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This picture shows the weevil sarting to change into a beetle
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This picture shows the early beetle
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This picture shows a fully formed beetle
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A number of years ago the chemical that was very widely used by growers was called ALDRIN this was very effective,( It was in powder form and added to the compost when being mixed up ), this product was withdrawn from use on safety grounds and it has taken the market some time to come up with replacements to control this menace which meet the Health and Safety requirements of our times.
Treatments for Weevils have been made easier in the last few years with the introduction of several new products. Provado is one commonly being used for a treatment to control this pest. It is simply mixed with water and poured into the pot. Readily available locally.
This systemic insecticide gives four months protection against Vine Weevil and 6 weeks against Whitefly, Blackfly and Greenfly. For use as a drench in all pot grown ornamentals grown inside and out. When you water your plants it kills grubs in the soil on contact. It is also taken up the roots, ending up in the leaves and plant tissue, so any sap-sucking insect attacking the plant is killed. Not for use on root vegetables or edible plants. Can be used on all ornamental plants in pots and containers indoors and outdoors.
Application will be required twice to give a full seasons protection
Provado is available at most garden centres.
Another method is to use packs of microscopic worms (eel worms or nematodes) which are watered into pots or open ground with a watering can or hose, and which kill the vine weevil grubs. The nematodes enter the grub, poisoning it and then feeding off it to increase their numbers. The nematodes are active any time when the soil temperatures are above 5 degrees, but to be effective you need to use them when the grubs are active and vulnerable. Application will be required twice to give a full seasons protection - once during March to end May to catch any grubs which may have overwintered and then a second during August to early November to treat freshly hatched grubs.
STEINERNEMA KRAUSSEI
This product has been sourced at www.ladybirdplantcare.co.uk
by many our members.
These are two of the products most commonly used by our members.