Articles
ADVANCES IN INTEGRATED CONTROL OF GERBERA PROTECTED CROPS
Trials on the greenhouse whitefly (T. vaporariorum) and serpentine leaf-miner L. trifolii) demonstrated that the use of yellow sticky traps is a very useful method of control against the two phytophagi.
In spring the sticky yellow traps (with or without quinomethionate treatments) solve the problem of whitefly infestation and allow the development of naturally introduced populations of chalcid wasp Encarsia formosa (Gahan) on the surviving whitefly progeny, giving satisfactory rates of parasitism.
In similar way a research programme started in 1982 to control the serpentine leafminer using sticky yellow plates to capture adults and some pyrazophos water sprays against the larvae inside the mines; it gave very good results, reducing largely established infestation.
On initial leafminer populations yellow sticky traps used alone can effectively protect the crops; in this case a naturally introduced population of Diglyphys isaea (Walk.) rises, with high rates of parasitism, despite the presence of the traps or of these and pyrazophos treatment.
This parasite, once established, gives alone a biological control of the crop, without insecticide treatments or use of yellow traps.
The described integrated control methods contain satisfactorily the red spider mite infestation, because either its population is killed by the quinomethionate treatments or else the predator mite, Phytoseiulus persimilis A.H., can naturally develop.
In both cases the red spider mite infestation is brought to an end.
The mentioned integrated methods of control prove to be a failure against other major and minor pests and specific treatments with pirimicarb or ethiofencarb must be given to eradicate aphids or with triazophos to kill noctuid larvae, Coccoidea and other minor pests.
The use of Bacillus thuringiensis Berliner against lepidoptera larvae in gerbera crops gives unsatisfactory results.
The use of triazophos or Avermectin B1 against the inside larvae of serpentine leafminer gives very effective results; these treatments and yellow sticky traps together solve the problem of leafminer infestation, but the first does not allow any development of D. isaea. These two chemicals have a partial (the triazophos) or total (the Avermectin B1) acaricide power and so they slacken or stop acarina infestation.