Joseph G. Morse

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A 2-yr study was conducted in a citrus orchard (Citrus sinensis L. Osbeck cultivar Valencia) to determine the influence of plant water stress on the population dynamics of glassy-winged sharpshooter, Homalodisca vitripennis (Germar). Experimental treatments included irrigation at 100% of the crop evapotranspiration rate (ET(c)) and continuous(More)
Anagrus epos Girault (Hymenoptera: Mymaridae) is a candidate for a classical biological control program targeting the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), in California. Because mass production of GWSS is expensive and labor-intensive, a factitious host that is more economical to produce is desirable(More)
In 1996, Scirtothrips perseae Nakahara (Thysanoptera: Thripidae) invaded California avocado orchards and moved pest management practices that relied almost exclusively on biological control to strategies dependent on insecticides to maintain thrips densities below economically damaging levels. By 1998, average losses due to thrips feeding damage in(More)
Xylella fastidiosa causes Pierce’s disease (PD), a serious disease in grapevines, and grapevine cultivars vary in susceptibility to X. fastidiosa in the field. The mechanism(s) by which this occurs has not been clearly elucidated. To explore possible mechanisms, X. fastidiosa cells from a PD strain were grown in pure xylem fluid of PD-susceptible(More)
Avocado thrips arrived in California in 1996. Since then, we have made substantial progress in our understanding of this pest. We now know the area of origin of the avocado thrips and have compiled an inventory of other potential pest thrips species on avocados in Mexico and Central America. Trials have helped us to identify several selective insecticides(More)
Dispersal and colonization of new areas by armored scale insects (Hemiptera: Diaspididae) is achieved by mobile first-instar nymphs, called crawlers. Few studies have considered the actual mechanisms by which crawlers disperse, and although crawlers are capable of actively wandering over short distances (generally < 1 m), their dispersal over longer(More)
BACKGROUND The efficacy of systemic applications of imidacloprid for the management of avocado thrips and avocado lace bug was determined in field trials. Following insecticide treatment by chemigation, leaves of appropriate age for each insect were sampled over a 6 month period and used for bioassays. Imidacloprid residues were measured by ELISA in leaves(More)
Field-grown orange (Citrus sinensis (L.) Osbeck) trees were subjected to all combinations of three levels of irrigation, three levels of fertilization, two levels of fungicide-nematicide applications, and two levels of growth regulator treatments during 1985-1987. Densities of the citrus red mite, Panonychus citri (McGregor), and densities and fruit(More)
The morphology, distribution, and hosts of two egg parasitoids, Ufens principalis Owen sp. n. and U. ceratus Owen sp. n. (Hymenoptera: Trichogrammatidae), are described for the first time. These species are compared to U. niger (Ashmead), the only species of Ufens s. str. currently described from the Nearctic, and diagnostic differences are presented. The(More)
A two-year study was conducted in a citrus orchard, Citrus sinensis L., to determine frequency of predation on glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar). A total of 1,578 arthropod predators, representing 18 taxa, were collected and assayed for the presence of GWSS egg protein by an enzyme-linked immunosorbent assay using a(More)