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Thomas B. Bruning, Michael H. Chaplin and Henry G. Taber

Ground water contamination resulting from continuous liquid fertilization technologies is a serious problem facing greenhouse growers in the United States. Rooted Dendranthema grandiflora Tzvelev. cultivar 'Iridon' cuttings were transplanted into 11 cm pots filled with a 50% peatmoss and 50% perlite (v/v) media containing 0.10, 0.21, 0.42, or 0.84 g N from a controlled release 12-10-17 plus minors fertilizer deposited directly below the transplanted cutting. Pots were assigned to a top-water or subirrigation treatment.

Subirrigation reduced the nitrate leachate concentration by as much as 250 ppm as compared with top-watering. Fertilizer N rate linearly decreased plant height in both of the irrigation treatments. Final dry weight of the shoot peaked at the 0.21 g N rate in both the irrigation treatments.

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Thomas P. Kuhar, Michael P. Hoffmann, Lydia J. Stivers-Young, Susan B. Sterrett and Michele Marini

Field cage experiments were conducted in Ithaca, N.Y. in 2001 to determine the yield effect of potato leafhopper (Empoasca fabae) infestations on early-stage beans (Phaseolus vulgaris). Yields of `Hystyle' snap beans and `Montcalm' dry kidney beans were significantly reduced when infested by potato leafhopper at the cotyledon, two-leaf, and four-leaf stages. For snap beans, no differences in yield response from potato leafhopper were observed among the three plant growth stages. For dry beans, there was a difference in yield response between cotyledon and four-leaf-stage plants. Dynamic economic injury levels for potato leafhopper on early-stage beans are suggested.

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Michael B. Thomas, Jonathan H. Crane, James J. Ferguson, Howard W. Beck and Joseph W. Noling

The TFRUIT·Xpert and CIT·Xpert computerbased diagnostic programs can quickly assist commercial producers, extension agents, and homeowners in the diagnosis of diseases, insect pest problems and physiological disorders. The CIT·Xpert system focuses on citrus (Citrus spp.), whereas the TFRUIT·Xpert system focuses on avocado (Persea americana Mill.), carambola (Averrhoa carambola L.), lychee (Litchi chinensis Sonn.), mango (Mangifera indica L.), papaya (Carica papaya L.), and `Tahiti' lime (Citrus latifolia Tan.). The systems were developed in cooperation with research and extension specialists with expertise in the area of diagnosing diseases, disorders, and pest problems of citrus and tropical fruit. The systems' methodology reproduces the diagnostic reasoning process of these experts. Reviews of extension and research literature and 35-mm color slide images were completed to obtain representative information and slide images illustrative of diseases, disorders, and pest problems specific to Florida. The diagnostic programs operate under Microsoft-Windows. Full-screen color images are linked to symptoms (87 for CIT·Xpert and 167 for TFRUIT·Xpert) of diseases, disorders, and insect pest problems of citrus and tropical fruit, respectively. Users can also refer to summary documents and retrieve management information from the Univ. of Florida's Institute of Food and Agricultural Sciences extension publications through hypertext links. The programs are available separately on CD-ROM and each contains over 150 digital color images of symptoms.

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J. Harrison Ferebee IV, Charles W. Cahoon, Michael L. Flessner, David B. Langston, Ramon Arancibia, Thomas E. Hines, Hunter B. Blake and M. Carter Askew

Chemical desiccants are commonly used to regulate tuber size, strengthen skin, and facilitate harvest for potato (Solanum tuberosum) production. Glufosinate is labeled for potato vine desiccation; however, limited data are available. Saflufenacil, a protoporphyrinogen oxidase–inhibiting herbicide, is an effective desiccant in other crops. Field research was conducted to evaluate glufosinate and saflufenacil as desiccants applied to ‘Dark Red Norland’ potato. Desiccants consisted of diquat, glufosinate, saflufenacil, glufosinate plus carfentrazone, and glufosinate plus saflufenacil applied at three timings, DESIC-1, DESIC-2, and DESIC-3, when size B potatoes averaged 43%, 31%, and 17% of total potato weight. Potato vine desiccation was more difficult at DESIC-1 and DESIC-2 because of immature vines. Diquat was the most effective desiccant 7 days after treatment (DAT), desiccating potato vines 88% at DESIC-1 7 DAT. Glufosinate alone desiccated potato vines 65% at the same timing; however, carfentrazone and saflufenacil added to glufosinate increased vine desiccation 8% and 16% compared with glufosinate alone, respectively. Vine desiccation by all treatments ranged 99% to 100% at 14 DAT. Desiccant and timing effects on skin set were determined using a torque meter before harvest. Skin set resulting from all desiccants and timings ranged between 1.88 and 2 lb-inch, and no significant differences were observed. No significant differences in yield were noted among desiccants. This research indicates that glufosinate and saflufenacil are suitable alternatives to diquat for potato vine desiccation; however, safety of saflufenacil applied to potatoes before harvest has not been determined.