A new cultivar of green tea ‘Haruto34’ was developed at the Tea Branch Facility, Miyazaki Agricultural Research Institute and released in 2016. ‘Haruto34’ was selected from seedlings of the crosses between ‘Saemidori’ and‘Sakimidori’, which were carried out in 1997.
The characteristics of‘ Haruto34’ are as follows :
‘Haruto34’ is extremely early budding and plucking time of the first crop is about two days earlier than that in ‘Saemidori’. The shape of the plant is of intermediate type and its growth is vigorous. ‘Haruto34’ is fairly resistant to tea gray blight (Pestalotiopsis longiseta (Spegazzini) Dai et Kobayashi), but it is susceptible to tea anthracnose (Discula theas-sinensis (I.Miyake) Moriwaki & Toy.Sato)and tea blister blight (Exobasidium vexans Massee). ‘Haruto34’ is vulnerable to mulberry scale (Pseudaulacaspis pentagona Targioni). ‘Haruto34’ is fairly resistant to cold injury damage in winter. The yield of ‘Haruto34’ is higher than that of ‘Yabukita’ and ‘Saemidori’. Sencha, Kamairicha to make with ‘Haruto34’ is high quality, as indicated by the bright green color of tea and mild aroma and taste. The amino acid content in the processed tea is high, whereas the tannin content is low. The covering cultivation of‘ haruto34’ around five days can greatly improve quality of the tea.
A red spot disease has been observed on leaves of a line of tea (Camellia sinensis) in Shizuoka Pref., in 2015. At first glance, the symptoms were similar to bacterial shoot blight caused by Pseudomonas syringae pv. theae (Hori 1915) Young, Dye and Wilkie 1978. But water-soaked lesions around spots were narrower than that observed in bacterial shoot blight, and the margin of water-soaked lesions was unclear. Further, no symptom on petiole has been observed, which was frequently observed as the first major symptom of bacterial shoot blight.
Therefore, identification of the causal agent was performed through isolation of pathogenic bacteria, artificial inoculation, physiological tests and phylogenic analysis based on 16S rRNA gene.
As a result, it became clear that this disease was identical with bacterial spot of tea caused by Acidovorax valerianellae Gardan, Stead, Dauga and Gillis 2003. This is the first report on the occurrence of this disease outside Kagoshima Pref.
We investigated parasitism by the egg parasitoid, Trichogramma spp., on Adoxophyes honmai and Homona magnanima eggs artificially placed on the plucking surface in tea fields. The rate of parasitism of A. honmai eggs had a small peak at early September and a large peak at late October and mid-November, during which the rate of parasitism of A. honmai eggs was about 30%. The rate of parasitism of H. magnanima eggs had a small peak from late September to early October and a large peak from late October to early November, during which the rate of parasitism of H. magnanima eggs was about 60% to 80%. The rate of parasitism of H. magnanima eggs was significantly higher than that of A. honmai eggs during investigation period. These results suggest that Trichogramma spp. has high potential as a biological control agent for H. magnanima.
Tea leaves that have been frozen and stored after steaming are generally used for processing of hand-rolled Japanese green tea (Temomi). However, there has not been a useful method for long-term storage of tea leaves for black tea processing. We stored withered tea leaves for period up to 5 months at -20℃. Tea shoots of the cultivar Benifuki grown in a field of Kanaya Branch Station, NARO Institute of Fruit Tree and Tea Science, were used for materials. They were plucked by a riding-type plucking machine in the first crop season and second crop season. They were withered in a fresh tea leaf container. Fresh leaf weights were reduced by forty and thirty percent at the end of the withering process in first crop season and second crop season, respectively. The withered tea leaves were packed in 5-layered laminated film pouches. The pouches were vacuumed, filled with nitrogen, frozen quickly at -30℃, and preserved at -20℃. The frozen tea leaves were defrosted in a refrigerator overnight before rolling. Rolling and subsequent processes were carried out just after finishing the withering process and after frozen storage for 1 month, 3 months, and 5 months. Since there were no water drops on the unfrozen tea leaves, there was no inconvenience in the following processes. The quality of the tea was evaluated by a sensory test with 9 panels. There was no difference between the score for the tea produced just after withering and the scores for the tea produced with tea leaves that had been frozen for 1, 3 and 5 months. We won the silver award at Owari-Asahi Black Tea Competition for tea made with tea leaves that were plucked in the first flush season and frozen for 3 months. It was clarified that it is possible to produce a good-quality black tea with tea leaves that are frozen after withering.