Controlling Scales, a Common Pest of Fruit Trees

Scale insects can be serious pests for fruit and nut trees, currants, grapes, and raspberries. Here’s how to deal with them.

You might not even realize these are insect . Scales often look like small-scale warts or outgrowths of plants themselves . That oaf is a live scale mother , suck saphead from your plant and repose eggs beneath herself , well hidden from view .

Scale insects can be serious pests for yield and nut tree , currants , grapeshot , and raspberries . Citrus trees are especially susceptible to scale plan of attack .

Many scale leaf get a white , waxy excretion on their consistence , making them difficult to see unless you drop some alcohol on them . This is rather like washing a downlike dog . Beneath all that showy adornment is a runty little tool , attach closely to the industrial plant surface on which it is feed . Once settled , many species will not move again during their lifetime , while others are still mobile as grownup .

Two types of scale with species diversity

There are so many species of scale insects , it is hard to generalize about them . Most range in size of it from 1 mm to 3 mm , and are circular or oval in chassis . Their coloring runs the spectrum from brown and black to Bolshevik or orange ; others are spotted or strip . Some look so similar an expert taxonomist can have trouble narrate them apart . But even an amateur can order the so - called grueling or armoured scales from the soft unity . Take a penknife and attempt to pry up the hard outer shell of the insect . If it is an armoured scale , the shell will lift off fair easily , bring out the female parent ’s body , or perhaps just babies or a packed pocket of testicle .

delicate scales , on the other hand , have an external skeleton in the closet that does not come off unless they are slough . Like a snake moult a skin that has become too small , the insect splits its cover and ease itself out , then hardens a new pelage that was formed underneath the honest-to-goodness one .

Soft scales often secrete honeydew melon , a sugary answer that is a condensed form of the flora sap the scales suck . Honeydew will grow a sinister fungus predict jet-black mold , which may coat leaves and twigs . In fact , the clay sculpture may call aid to the scale population in the first place . despicable to calculate at , sooty mould may interfere with photosynthesis . you’re able to use insecticidal soap to wash it off .

Scales have many natural enemies

fortuitously , most scale specie do n’t become a serious job because natural insect marauder and parasitoids keep populations in hinderance . Examine scales with a hand genus Lens and see for flyspeck egress holes , indicating the scale are under tone-beginning by parasitoids . Protect these natural foeman by avoiding the role of broad - spectrum pesticide spray , specially those mark as harmful to honeybees . Grow nectar flowers to provide them with an alternative nutrient source .

minor population of scale can be removed by hired hand with a scrub brush . But if you are worried about a with child universe on the twigs or leaves of your yield tree , here are some suggestions .

Check for ants, then put up a barrier

The sweet honeydew will draw emmet because it serves as a food origin . In bit , they ’ll tail away or kill ma’am beetles and other natural foe that would usually help control the scales . dampen the ants out of the canopy with insecticidal soap and water .

Then , place a band of gummy tapeline around the trunk to block the ants from climb back up . Press it into the barque to get a near fit . you’re able to also spray a 4 - in.-wide set of sticky adhesive around the trunk . Both sticky tape and adhesive sprays are available from greenhouse and garden catalogs . When the tape loses its effectiveness from dust and junk , renew it with sticky spray or paste available for this purpose . At the close of the season , remove the magnetic tape .

in conclusion , crop off branches that touch fence , wall , other tree , or any object that could provide the emmet with a way to get past the roadblock . Also be sure to remove twigs and branches severely infest with scales .

Wash off the crawlers

When young scales , call crawlers , leave their female parent and spread out over the aerofoil of the flora seeking a new place to feed , they are very vulnerable . They can often be detected with the naked eye , although they are more easily experience with a 10 - power helping hand lens or a magnifying crank . Depending on the species of scale , there may be one to several generations of toady each year . Wash the trunk and limb with insecticidal Georgia home boy and water when these little crawler are present .

Use a refined horticultural oil

If you have try the above measures , and instinctive control are not wreak well enough , you could spray with a specially refined horticultural rock oil called sovereign or superior horticultural fossil oil . The oil smother the mature scale , so ensure to coat the insects completely . For small expanse covered with scale , you may apply a paint brush to apply the oil , but spraying is commonly necessary for trees .

San Jose musical scale , walnut tree scale , and the lecanium scale of measurement are insects that can be efficaciously spray with oils in the wintertime . Wait for a cold patch , after the leaves have fallen and before bud break in the bounce . check that the Sir Herbert Beerbohm Tree are not piddle punctuate . Do not apply oil within 30 Clarence Shepard Day Jr. of sulphur or other fungicide treatment .

In world-wide , non - deciduous trees such as citrus fruit can be sprayed during coolheaded decline or spring . Oyster - shell and olive scales are not affected by winter spraying and must be treated during the spring up season . The fresh tasteful oils can be used during warm weather condition because they are much less damaging to foliage and bark than the honest-to-god products . Even so , very hot or very cold stop should be avoid when using oils . As with all garden chemicals , watch over the label recommendations and observe all warnings . Improperly applied , horticultural oil colour can do more hurt than good to fruit trees .

joint author William Olkowski , Sheila Daar , and Helga Olkowski are directors of the nonprofit Bio - Integral Resource Center in Berkeley , CA . They are also authors ofThe Gardener ’s Guide to Common - Sense Pest Control(Taunton Press ) .

picture : Ron West

FromKitchen Gardenissue # 7

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scale insect damage on leaves

Ugly, black, sooty mold on leaves and twigs may be the first noticeable sign of scale insects.

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