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Albert N. Kishaba, Steven J. Castle, Donald L. Coudriet, James D. McCreight, and G. Weston Bohn

The spread of watermelon mosaic virus by the melon aphid (Aphis gossypii Glover) was 31%, 74%, and 71% less to a melon aphid-resistant muskmelon (Cucumis melo L.) breeding line than to the susceptible recurrent parent in a field cage study. Aphid-resistant and susceptible plants served equally well as the virus source. The highest rate of infection (97.9%) was noted when target plants were all melon-aphid susceptible, least (26.7%) when the target plants were all melon-aphid resistant, and intermediate (69.4%) when the target plants were an equal mix of aphid-resistant and susceptible plants. The number of viruliferous aphids per plant required to cause a 50% infection varied from five to 20 on susceptible controls and from 60 to possibly more than 400 on a range of melon aphid-resistant populations. An F family from a cross of the melon aphid-resistant AR Topmark (AR TM) with the susceptible `PMR 45' had significantly less resistance to virus transmission than AR TM. Breeding line AR 5 (an aphid-resistant population with `PMR 5' as the recurrent parent) had significantly greater resistance to transmission than other aphid-resistant populations.

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Francisco Javier Palomares-Rius, Ana Garcés-Claver, María Belén Picó, Cristina Esteras, Fernando Juan Yuste-Lisbona, and María Luisa Gómez-Guillamón

mildew incited by Podosphaera xanthii (Castagne) U. Braun & N. Shishkoff ( Shishkoff, 2000 ) and the yellowing incited by Cucurbit yellow stunting disorder virus (CYSDV) and the incidence of the cotton-melon aphid, Aphis gossypii are three of the

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John Klingler, Irina Kovalski, Leah Silberstein, Gary A. Thompson, and Rafael Perl-Treves

Resistance to cotton-melon aphid (Aphis gossypii Glover) segregated as a single dominant gene in a melon (Cucumis melo L.) mapping population derived from the cross `Top Mark' × PI 414723. Sixty-four F2-derived F3 families were used to map the aphid resistance locus, Vat, with respect to randomly amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP) markers. RFLP markers NBS-2 and AC-39 flanked Vat at distances of 3.1 cM and 6.4 cM, respectively. NBS-2 is homologous to the nucleotide binding site-leucine-rich repeat (NBS-LRR) superfamily of plant resistance genes. Another homolog of this superfamily, NBS-5, was positioned ≈16.8 cM from Vat, raising the possibility that Vat resides in a cluster of NBS-LRR paralogs. RFLP marker AC-8, which has similarity to plant lipoxygenases, was positioned at ≈5.5 cM from Vat. Monogenic resistance to A. gossypii has been identified in two sources of melon germplasm, Indian accession PI 371795 (progenitor of PI 414723) and Korean accession PI 161375. To test for an allelic relation between the genes controlling aphid resistance in these two distinct germplasm sources, melon plants of a backcross population from a cross between two resistant lines having Indian- or Korean-derived resistance were infested with aphids. At least 90 out of 92 segregating progeny were aphid resistant, suggesting that the same resistance gene, Vat, is present in both sources of melon germplasm.

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Claudio C. Pasian, Daniel K. Struve, and Richard K. Lindquist

The effectiveness of two application methods of the insecticide imidacloprid in controlling 1) melon aphids (Aphis gossypii Glover) on `Nob Hill' chrysanthemum (Dendranthema ×grandiflora Ramat) plants and 2) silverleaf whitefly (Bemisia argentifolii Bellows & Perring) on `Freedom Red' poinsettia (Euphorbia pulcherrima Wild.) were compared. Plants were grown in containers with their interior covered by a mixture of flat latex paint plus several concentrations of imidacloprid (0, 10, 21, 42, and 88 mg·L−1), or treated with a granular application of the insecticide (1% a.i.) according to label recommendations. All imidacloprid treatments effectively reduced aphid survival for at least 8 weeks. The two most effective treatments were the granular application (10 mg a.i.) and the 88-mg·L−1 treatment (0.26 mg a.i). All imidacloprid treatments effectively reduced whitefly nymph survival. The 42- and 88-mg·L−1 treatment and the granular application (1% a.i.) were equally effective in reducing nymph numbers in lower poinsettia leaves. None of the plants given treatments with paint exhibited any phytotoxicity symptoms. These results suggest the possibility of a new application method for systemic chemicals with the potential of reducing the release of chemicals to the environment. Paint and imidacloprid mixes are not described in any product label and cannot be legally used by growers. Chemical name used: 1-[(6-chloro-3-pyrimidil)-N-nitro-2-imidazolidinimine (imidacloprid)

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Fred T. Davies Jr., Chunajiu He, Amanda Chau, Kevin M. Heinz, and Andrew D. Cartmill

This research details the influence of fertility on plant growth, photosynthesis, ethylene evolution and herbivore abundance of chrysanthemum (Dendranthema grandiflora Tzvelev `Charm') inoculated with cotton aphids (Aphis gossypii Glover). We tested five fertility levels that consisted of 0%, 5%, 10%, 20%, and 100% (375 ppm N) of recommended nitrogen levels. Aphid abundance was greatest at high fertility. Fertility affected the vertical distribution of aphids. A higher population of aphids were observed in physiologically mature and older leaves at low fertility, whereas at high fertility young leaves had 33% more aphids than older, basal leaves. Aphids depressed plant vegetative and reproductive growth, and altered carbohydrate partitioning at high fertility. Aphid-inoculated (AI) plants at high fertility had increased specific leaf area [(SLA), i.e., thinner leaves] and greater leaf area than aphid-free (NonAI) plants. Aphids caused greater ethylene production in reproductive buds and young leaves of high fertility plants, but had no effect on ethylene evolution in physiologically mature or older, basal leaves. Plant growth, leaf nitrogen (N), phosphorus (P), iron (Fe) and manganese (Mn) increased at higher fertility, as did chlorophyll and photosynthetic rates. Leaf N was highest in young and physiologically mature leaves compared to basal leaves. Aphids decreased leaf N and P. Aphids reduced photosynthesis in young leaves of high fertility plants, whereas physiologically mature and older leaves were unaffected.

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J.K. Collins, P. Perkins-Veazie, N. Maness, and B. Cartwright

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Kelechi Ogbuji, Gloria S. McCutcheon, Alvin M. Simmons, Maurice E. Snook, Howard F. Harrison, and Amnon Levi

)] and aphids [ Aphis gossypii Glover and Myzus persicae (Sulzer)] are major pests that feed on and transmit viruses to watermelon plants ( Simmons et al., 2010 ; Simmons and Levi, 2002 ). However, several C. colocynthis PIs possess resistance to

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J.R. Fisher and S.G.P. Nameth

Cucumber mosaic virus (CMV) was isolated from the perennial ornamental mint, Ajuga reptans L. `Royalty', using melon aphids (Aphis gossypii Glover). The isolate and its associated satellite RNA (satRNA) were biologically and chemically characterized. The satRNA was cloned and sequenced and is 338 nucleotides long and does not induce lethal necrosis on `Rutgers' tomato (Lycopersicon esculentum Mill.) or severe chlorosis on tobacco (Nicotiana L. spp.). The virus is ≈28 to 30 nm in diameter and reacts to CMV serological subgroup I antibodies. The virus is able to infect `Black Beauty' squash (Cucurbita pepo L.), cucumber (Cucumis sativus L.), and `Howden' pumpkin (Cucurbita pepo) but is not able to infect green bean (Phaseolus vulgaris L.) or cowpea [Vigna unguiculata (L.) Walp. ssp. unguiculata]. The virus is able to efficiently replicate its satRNA in tobacco and `Black Beauty' squash but replication is less efficient in cucumber, based on accumulation of double-stranded satRNA.

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P.M. Perkins-Veazie, J.K. Collins, N. Maness, and B. Cartwright

High populations of melon aphid (aphis gossypii) reduce cantaloupe plant growth and yield; effects on subsequent fruit quality are unknown. The purpose of this study was to evaluate fruit quality from plants with high and low aphid populations. Up to 50% of melons from plants having high aphid populations were unmarketable due to surface sooty mold. Melons from plants with high or low aphid populations, but not cultivars, were similar in flesh quality. The internal color of `Perlita' and `Sweet Surprise' was a more yellow hue while that of `TAM Uvalde' was more orange. `Sweet Surprise' melons were lower in percent soluble solids concentration and titratable acidity, but were higher in mg fructose/ml juice compared to the other cultivars. A trained taste panel of 30 people evaluated melons from 2 cultivars showing little damage from melon aphid infestations and from 2 cultivars exhibiting high damage. All melons had similar taste qualities with acceptable sweetness, flavor, odor and texture. These results show that high aphid populations deleteriously affect cosmetic appearance, but not flesh quality, of melons.

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Mario Orozco-Santos, Octavio Perez-Zamora, and Oscar Lopez-Arriaga

The effect of floating rowcover and transparent polyethylene mulch was evaluated on insect populations, virus disease control, yield, and growth of muskmelon (Cucumis melo L.) cv. Durango in a tropical region of Colima state, Mexico. Aphids (Aphis gossypii Glover and other species), sweetpotato whitefly (Bemisia tabaci Gennadius), beetles (Diabrotica spp.), and leafminer (Lyriormyza sativae Blanchard) were completely excluded by the floating rowcover while the plots were covered (until perfect flowering). Transparent mulch reduced aphids and whitefly populations, but did not show effect on leafminer infestation. The appearance of virus diseases of plants was delayed for 2 weeks by floating rowcover with respect to control (bare soil). Also, the transparent mulch reduced the virus incidence. The yield and number of fruit were positively influenced by floating rowcover and transparent mulch. Plot with transparent mulch combined with floating rowcover yielded nearly 4-fold higher (50.9 t·ha–1) than that plots with bare soil (13.1 t·ha–1). The yield from plots with floating row cover on bare soil was of 38.3 t·ha–1, while in the transparent mulch plots it was of 23.1 t·ha–1. The results of this work shows the beneficial effects of floating rowcover and transparent mulch in dry tropical conditions.