. California greenhouse pests and their control. Insect pests; Greenhouse plants. TUetfauU o£ (fatfaol BIOLOGICAL CONTROL The insect pests occurring in green- houses are likely to be isolated from the natural enemies which accomplish vary- ing degrees of control under outdoor con- ditions. Biological control in greenhouses consists for the most part of artificially rearing and liberating certain of these enemies. The use of such predators and parasites is impractical when they are killed by insecticides which may be used for the control of other pests. The ladybird beetle, Cryptolaemus montrou
. California greenhouse pests and their control. Insect pests; Greenhouse plants. TUetfauU o£ (fatfaol BIOLOGICAL CONTROL The insect pests occurring in green- houses are likely to be isolated from the natural enemies which accomplish vary- ing degrees of control under outdoor con- ditions. Biological control in greenhouses consists for the most part of artificially rearing and liberating certain of these enemies. The use of such predators and parasites is impractical when they are killed by insecticides which may be used for the control of other pests. The ladybird beetle, Cryptolaemus montrouzieri Mulsant, is a voracious feeder on mealybugs in both larval and adult stages. This beetle was originally collected in Australia, and colonies were liberated in California citrus orchards many years ago. A number of growers have used them in gardenia ranges. Their results have been variable, but in general the mealybug populations have been con- siderably decreased but not eliminated. Conditions unfavorable for the develop- ment of the beetles may occur during the winter, and new liberations are then necessary in the spring. The Sicilian parasite, Leptomastidea abnormis (Girault), also has been re- leased to a limited extent in gardenia ranges for control of the citrus mealybug. In other parts of the country parasitic wasps, Encarsia formosa Gahan, have been released in greenhouses infested with the greenhouse whitefly. Very satis- factory control has been reported. HEAT TREATMENT Steam Sterilization Sterilization of the soil with steam is a well-known practice for the control of many pests. Many plant disease organ- isms and weed seeds also may be killed by steam, and conditions more favorable in general to plant growth may be Fig. 52. Larvae of a ladybird beetle which feeds on mealybugs. The soil should be dry and loose at the time of steaming. The type and condition of the soil and the amount of steam avail- able per unit area are important consid- erations f
Size: 1346px × 1857px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, booksubjectgreenhousepl, booksubjectinsectpests
