PLANT PROTECTION 1 â Pests, Diseases and Weeds

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PLANT PROTECTION 1 – Pests, Diseases and Weeds 4. Monitor for mealybugs when they are known to be active and record findings. Check roots of wilting plants, for the presence of mealybugs, sooty mould, honeydew, ants. Also monitor for biological control agents. If using an IPM program it will tell you when and where to look, what and how to monitor, eg adults, crawlers, main parasites and predators. Desire Sticky traps are available for citrophilous mealybug: http://insense.com.au/products.htm 5. Thresholds vary according to the crop and method of proposed control. Some pest scouts prefer to use a lower action level early in the season depending on the variety, populations of mealybugs and predators, and degree of parasitism. How much damage can you accept? 6. Action. Take appropriate action if threshold is reached. 7. Evaluation. Review your program and recommend improvements. Monitor trees and bins after treatment, compare results with the previous season. Control methods Cultural methods. Adequate irrigation helps reduce effects of infestation by replacing sap lost to sucking insects. Maintain plant vigour. Cover crops decrease temperatures, increase humidity in summer favouring natural controls. Sanitation. Discard severely infested small plants of little value in greenhouses and houses. Prune off badly affected sections of plants. Minor infestations on house plants may be picked off and killed or removed by dabbing with a small brush or cotton bud dipped in methylated spirits. This is tedious and time-consuming, will not eradicate them and may break stems and foliage of soft-foliaged plants. Plants may be washed with or dipped upside down in warm soapy water and then rinsed in clear tepid water. Large plants may be sponged. Sooty mould in the navels of mature oranges is not easy to remove by washing before packing. Throughly disinfest recycled pots to avoid transferring eggs or nymphs from crop to crop. If root mealybugs, thoroughly disinfest nearby gravel including beneath plastic and weed mats. Biological control. Natural controls are not always effective. Parasites and predators are discouraged by dust and ants (attracted by honeydew) and some pesticides. – Predators include lacewing larvae (Chrysopa sp., Oligochrysa lutea), mealybug ladybird. – Parasites include various wasp parasites, eg Anagyrus, Leptomastix. – Root mealybugs are underground and not so accessible to natural controls. Commercially available. – Main parasite is the small wasp (Leptomastix dactylopii) which may be reared or purchased. Two parasites (Coccophagus gumeyi and Tetracnemoides brevicornis) have been released to suppress citrophilous mealybug. – Main predator is the mealybug ladybird (Cryptolaemus montrouzieri) which is black and red, 3.5 mm long, lays its yellow eggs singly in mealybug egg sacs or near clusters of mealybugs. Other ladybirds include Rhyzobius ruficollis and Scymnus spp. Larvae of the cecid fly (Diadiplosis koebelei) and lacewings (Mallada spp.) also feed on mealybugs. – List of suppliers www.goodbugs.org.au Resistant/Tolerant varieties. Some plants are very susceptible, eg African violet, citrus, ferns. Plant quarantine. Nurseries growing very susceptible species should quarantine and examine new stock brought in from external sources. Keeping mealybugs out of nurseries is preferable to controlling them once they are established. Pest-tested planting material. Only propagate from and purchase mealybug-free stock. Examine all stock plants. Insecticides. Mealybugs are difficult to control with insecticides because they feed in protected places, are covered with water-repellent wax and lay large numbers of eggs which develop quickly under ideal conditions (see also page 170). Glasshouses may require regular treatments. Apply insecticides to crawlers - the arrival of ants indicate crawlers are about! Use a hand lens to identify them so you can initiate control measures. Control ants if present outdoors in spring. Systemic insecticides are generally more effective than contact ones. Apply high volume sprays to fully wet canopy, application must be thorough. If mealybugs are on roots of plants in pots, wet soil in pot thoroughly the night before treatment to lesson chance of root damage. Place pot in basin and allow insecticide solution to soak in. Use enough liquid to wet the complete root zone. Table 30. Longtailed mealybug – Some insecticides. What to use? HOUSE PLANTS Only use sprays labeled for indoor use. GLASSHOUSES Seek advice OUTDOORS Insecticides registered for mealybugs generally: Group 1A, eg Bugmaster (carbaryl) Group 1B, eg Rogor (dimethoate); maldison; Folimat (omethoate) Group 3A, eg pyrethrins, Baythroid (cyfluthrin); Procide , various (bifenthrin) Group 4A, eg Confidor ,various (imidacloprid); Maxguard (acetamiprid); Sumarai (clothianidin) Group 16, eg Applaud (buprofezine) Spray oils, eg certain petroleum, paraffinic and botanical oils Soap sprays, eg BugGuard , Natrasoap (potassium salts of fatty acids) When & how to apply? Take plants outside for treatment unless label advises otherwise. Oils may injure many indoor plants, especially maiden hair ferns. Regular treatments may be required. Outdoors avoid spraying mealybug-prone plants for other pests and diseases (this will kill any natural controls). Control ants. Consider spot spraying. Only after monitoring and if natural enemies cannot cope with infestation. Contact sprays are only effective if mealybugs are actively moving over the plant. Adult mealybugs that have developed their waxy covering are difficult to kill with contact pesticides. Contact sprays are devastating to all beneficials. Contact sprays can be effective against crawlers. Systemic sprays give good control of adult mealybugs that are feeding. Once they have stopped feeding it is too late to control them. Some systemic sprays are not so harmful to some beneficials. Spray oils are only effective against young stages of mealybugs but are less harmful to beneficials than many insecticides. Loosens sooty mould. Oil sprays smother nymphs. 162 Insects and allied pests - Hemiptera (bugs, aphids, etc)
PLANT PROTECTION 1 – Pests, Diseases and Weeds Fig. 111. Some soft scales (Family Coccidae) (some other honeydew-producing scales are included) Wattle tick scale (Cryptes baccatus). Drops of honeydew. PhotoCIT, Canberra (P.W.Unger). Gumtree scale (Eriococcus coriaceus). Small male scales and larger female scales. PhotoNSW Dept of Industry and Investment. Black scale (Saissetia oleae) on stems. PhotoCIT, Canberra (P.W.Unger). Frosted scale (Eulecanium pruinosum). PhotoNSW Dept of Industry and Investment. Soft brown scale (Coccus hesperidum) on stems and leaf midribs. PhotoNSW Dept of Industry and Investment. White wax scale (Ceroplastes destructor) on stems and leaf midribs. PhotoNSW Dept of Industry and Investment. Cottonycushion scale (Icerya purchasi). Fluted egg sac. PhotoNSW Dept of Industry and Investment. Insects and allied pests - Hemiptera (bugs, aphids, etc) 163
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Insect secretions PLANT PROTECTION
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Control methods Cultural methods.
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Root structure of dock (Rumex spp.)
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PLANT PROTECTION 1 â Pests, Diseases and Weeds

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PLANT PROTECTION 1 â Pests, Diseases and Weeds