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Tina P. Thomas, Madhurababu Kunta, John V. da Graça, Mamadou Sétamou, Mani Skaria, and Apurba Bhattacharya

Root rot caused by Phytophthora nicotianae and P. citrophthora is one of the most serious and economically significant diseases of citrus ( Graham and Timmer, 1994 ; Timmer and Menge, 1988 ). Phytophthora spp. can infect almost all parts of

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Scovia Adikini, Settumba B. Mukasa, Robert O.M. Mwanga, and Richard W. Gibson

obtain planting materials, leading to late planting ( Gibson et al., 2009 ; Namanda et al., 2011 , 2012 ; Yanggen and Nagujja, 2006 ). The health status of such sprouts is not known; but, if infected by virus, they may act as a local source of inoculum

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Lisa A. Beirn, William A. Meyer, Bruce B. Clarke, and Jo Anne Crouch

controlled environmental conditions. At present, turfgrass breeders are reliant on natural field infections to evaluate their germplasm. This can be a complicated and unreliable process, as multiple rust species can infect KBG ( Beirn et al., 2011 ) and

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Kelly T. Morgan, Robert E. Rouse, and Robert C. Ebel

). By 2015, about 80% of citrus trees in Florida were infected with the HLB pathogen ( Singerman and Useche, 2016 ) making tree removal to reduce the source of inoculum impractical ( Gottwald, 2010 ) and a need for alternative management practices

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M. Ahmedullah and P. Bristow

Concord blueberries treated with biocontrol fungi (Trichoderma and Gliocaladium) both at 1 and 2x rates and with fungicides benlate + captan + B 1956 and Tween for controlling botrytis flower blight were stored at 32F. Trichoderma (2x)-treated fruit was 71% without infection; Gliocaladium (2x)-treated fruit 69%, compared to 57% from untreated control. Momentum Transfer Generator (MTG) readings indicating fruit firmness ranged from 474 to 494 for the above treatments, indicating that fruit firmness was not affected by the treatments. Concord blueberries from bushes infected with blueberry scorch carla virus showed no difference in fruit firmness compared to healthy berries either before or after 7 weeks of storage at 32F.

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Madhurababu Kunta, John V. da Graça, Nasir S.A. Malik, Eliezer S. Louzada, and Mamoudou Sétamou

differentiate live from dead cells. A similar study using both qPCR and conventional PCR (cPCR) to amplify 16S rDNA showed that CLas is unevenly distributed in infected bark, leaf midribs, roots, and floral and fruit parts, ranging from 14 to 137,031 cells/μg of

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Mary Helen Ferguson, Christopher A. Clark, and Barbara J. Smith

. virgatum syn. V. ashei ) plants with X. fastidiosa resulted in no detected infection in ‘Premier’ and in local colonization of two of six ‘Powderblue’ plants. In infected ‘Powderblue’ plants, symptoms did not progress past the inoculated stem within a

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Michelle Carratu and Roger J. Sauve

Phytophthora cinnamoni infected Rhododendrons subjected to moderate moisture levels had greater survival rates than at the wet or dry levels. We potted rooted cuttings of Rhododendron L. hybrid, “Lee's Dark Purple” in 3 liter containers using a mixture of 3 pine bark: 2 coarse builder's sand: 1 Canadian peat moss (by vol.) and infected them with P. cinnamoni. Tensiometers maintained the moisture levels of the treatments at 0, -5, -10, -15, and -20 kPa. After 90 days, measurements of the plants revealed virtually curvilinear results, with the highest survival rate, plant and root weights at -5 and -10 kPa. Investigation continues on susceptibility of Rhododendrons to P. cactorum, P. cryptogea, P. cinnamoni, and P. citrophthora under wet and dry conditions.

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Yonghong Guo, Zong-Ming Cheng, and James A. Walla

Five simplified DNA preparation procedures for polymerase chain reaction (PCR) amplification were tested for detection of phytoplasmas from infected herbaceous and woody plants. Thin freehand cross-sections made from infected plant tissues and stored in acetone were used as sources for DNA preparation. The tissue sections were treated by: 1) grinding in sodium hydroxide; 2) sonicating in water; 3) microwaving in water; 4) boiling in sodium hydroxide; or 5) placing directly in PCR tube. PCR amplification was performed with a universal phytoplasma-specific primer pair in a reaction buffer containing 0.5% (v/v) Triton X-100, 1.5 mm magnesium chloride, and 10 mm Tris-HCl. All five procedures provided phytoplasmal template DNA for successful PCR amplification from infected herbaceous plants {periwinkle [Catharanthus roseus (L.) G. Don (periwinkle)], carrot (Daucus carota L.), maize (Zea mays L.)}, while the grinding, microwaving, and boiling procedures also allowed positive amplification from a woody plant [green ash (Fraxinus pennsylvanica Marsh.)]. The quality of the resulting DNA was adequate for subsequent identification of the aster yellows and ash yellows phytoplasmas through nested-PCR using phytoplasma group-specific primer pairs. These methods provide remarkable savings in labor and materials, making disease testing and indexing of plant materials much more attractive.

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Frank A. Buffone and Don R. La Bonte

Chlorotic Leaf Distortion (CLD) is a common disease of sweetpotato caused by Fusarium lateritium. This fungus is unique among Fusarium species in that it grows on the epidermis of leaves and shoot tips of sweetpotato. Fusarium lateritium appears as a white epiphytic material and under bright sunlight causes leaf chlorosis. When cloudy weather persists for several days, all symptoms disappear.

Researchers who use RAPD to examine banding patterns of sweetpotato DNA assume that foreign DNA present in the cTAB extract is quantitatively low and will not appreciably amplify and appear as bands. In this study we found the modified cTAB procedure used to amplify sweetpotato DNA also amplifies DNA of Fusarium lateritium cultures. DNA banding patterns of infected leaves was compared with those free of the disease. No differences in banding patterns were observed in this preliminary study.