A method to isolate Clavibacter michiganensis subsp. michiganensis (Cmm) using ImmunoStripTMCmm (IS), a commercial strip to diagnose bacterial canker on tomato (Solanum lycopersicum) caused by Cmm, was developed. A distinct positive antigen-antibody reaction line developed for suspensions of Cmm over 2×105 cfu/ml. The Cmm-positive band on the IS was then cut from the strip, friction-ground in 0.1 ml sterilized distilled water, and a loopful of suspension was plated on potato semisynthetic agar for a fairly selective isolation of Cmm.
An unknown stem rot of pitaya (H. undatus; Cactaceae) was observed in orchards in Okinawa, Japan in 2005. A Gilbertella species was isolated from diseased stems, and typical symptoms were reproduced after inoculating wounded stems with isolates. The causal fungus was identified as G. persicaria (Eddy) Hesseltine on the basis of morphological characteristics, growth and germination temperature, and rDNA-ITS sequence homology. The name Gilbertella stem rot (Kukigusare byo) was proposed for this new disease.
Homogenization of plant tissue is an important process for various experiments with plants. Because the commonly used mortar and pestle is laborious and time-consuming, the Finger Masher, a new type of vessel made of flexible plastic with a rough interior surface, was developed by Mizuho-Medy Co. Ltd. for rapid, easy homogenizations. Hands become too fatigued, however, when many samples must be processed. Therefore, we developed an automatic macerating machine for the Finger Masher to handle many samples in a short time. ELISA values obtained for Apple stem grooving virus or Cucumber mosaic virus in plant samples extracted with the automatic macerating machine were similar to those obtained by conventional homogenization with a mortar and pestle. The time for sample preparation was also much shorter than for other methods.
In 1997, Phytophthora rot caused serious losses to ginger (Zingiber officinale Rosc.) production in Kochi Prefecture, Japan. In the field in early summer and autumn, water-soaked rot on basal pseudostems and brown rot on rhizomes were first observed, then plants developed stem blight. The disease also developed on rhizomes stored at 15°C in the dark. A Phytophthora sp. was consistently isolated from the symptomatic lesions and caused the same symptoms after inoculation with the isolates. The identical Phytophthora sp. was then reisolated. White stellate colonies grew on PDA at a minimum temperature of 10°C, optimum of 23°C and maximum of 30°C. Sporangia were ovoid, ellipsoid, globose and distorted (variable) with one or two apices, noncaducous, 30–90 × 20–50 (average 50.0–56.1 × 25.0–32.6) μm, with a length to breadth ratio of 1.5–1.7:1. Nucleotide sequence of the r-DNA ITS regions agreed well with those of Phytophthora citrophthora (R. E. Smith and E. H. Smith) Leonian previously reported. Based on these results, the isolate was identified as P. citrophthora. This report is the first of a disease of ginger caused by P. citrophthora, and we propose the name “Phytophthora rot” for the disease.