FRUIT PESTS: Spotted Wing Drosophila & Apple maggot

An excerpt from Linda Gilkeson's latest bulletin:

It is now more important than ever for gardeners to have access to durable insect netting to protect against two, quite nasty, fruit pests that are now established in the region:

Spotted wing Drosophila (a species of vinegar fly), which attacks stone fruit, berries, Asian pear, grapes and numerous wild plants (more info: http://www.agf.gov.bc.ca/cropprot/swd.htm);

To date in British Columbia, spotted wing drosophila has been confirmed infesting wild and cultivated raspberry and blackberry (Rubus), blueberry (Vaccinium), strawberry (Fragaria), table grape (Vitis), cherry, peach, nectarine, apricot, plum (Prunus), and suspected in hardy kiwifruit (Actinidia).  Wild hosts confirmed include Oregon grape (Mahonia aquafolium), elderberry (Sambucus), currant (Ribes), dogwood (Cornus kousa), mulberry (Morus), salmonberry (Rubus spectabilis), thimbleberry (Rubus parviflorus) and salal (Gaultheria shallon)

Apple maggot (a species of fruit fly) (more info: http://cru.cahe.wsu.edu/CEPublications/eb1928/EB1928.pdf)

Bug Mesh: Carrot rust fly, cabbage root maggot, currant fruit fly and now these newly introduced flies infest roots or fruits with little white maggots.  The easiest fix for a home gardener is a barrier that simply stops the adult flies from laying their eggs on plants or fruit. For decades gardeners have been making do with floating row covers for this purpose. The lightest weight row cover is the best for insect control, but it tears easily. The thicker row cover fabrics last longer and are fine for short term use to keep off insects, but they exclude more light than is desirable for crops, such as carrots, that must be covered for the whole season. They are not strong enough to cover fruit trees.

Enter 'bug net' or insect netting--sturdy, long-lasting, knitted poly monofilament fabric, sold in different widths and mesh size for different pests. Anyone from Great Britain knows all about these product because gardeners there have had them for years. Or check out Australian gardening web sites to see their variety of bug mesh products in that land of fruit flies. The fabric can be used to cover vegetable beds supported on hoops. It can be sewn into bags big enough to drop over a whole berry bush or small fruit tree or made into small bags to cover individual fruit or bunches of grapes.

So, I hope all of you go into your local garden centre and 'bug' them to start carrying one of the bug mesh products (there are several suppliers of different brands) so that you can buy lengths to suit your needs. Or get together with some other gardeners and order a wholesale roll to divide up. Last year on Salt Spring some of us ordered  100 m rolls of ProtekNet brand from Dubois Agrinovation (in Montreal) www.duboisag.com/ .  Various widths are available, but get at least the 60 gr mesh size, which is small enough for carrot rust fly, cabbage maggot and fruit flies.  So far, nurseries that I know of stocking the knitted monofilament bug mesh are Dinter Nursery in Duncan and Russell Nursery in North Saanich.

Fruit Bags: Using paper, bug mesh or fabric bags to protect apples, peaches, pears and clusters of grapes from insects is a well-established method for commercial organic production. Gardeners have been devising their own bags, using those translucent paper bakery bags or small lunch bags. Where they can get them, some people have been buying the specially designed Japanese fruit bags with a integral twist tie used by the commercial orchardists. Years ago I sewed up a set of fabric bags with drawstring tops to keep racoons and insects out of my table grapes. They have proven their worth many times over and are quick to install; I am still using the same bags so the investment in time to make them was well worth it. BUT, now, with apple maggot upon us (they have been found on Salt Spring and  Vancouver Island) gardeners will want to bag their apples. And with spotted wing Drosophila getting into all kinds of other fruit, including Asian pears, disposable fruit bags would be useful for these crops.

Photo courtesy of WSU Fact Sheet http://cru.cahe.wsu.edu/CEPublications/eb1928/EB1928.pdf


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