Maui Vegetable Notes July 13, 1989 CHINESE CABBAGE VARIETY TRAIL The summer Chinese cabbage variety trial was conducted to determine the resistance of the cultivars to the Bacterial Butt-rot. The seeds were planted on April 5, 1989, and the seedlings were transplanted on May 9. Harvesting was done over a 3 week period, beginning from June 20 and ending on July 5, 1989. There was only one replication of this trial. For each cultivar, two rows of 30 plants were planted. Of the two row, one row was harvested and the other was left for the growerc to evaluate the cultivar. Therefore, the data in Table 1 is based on 30 plants per cultivar. The three early cultivars, Dancer, Saladeer and Sonnet bolted in the,peedling trace prior to tranaplanting. All of the Tropical cultivars bolted on or about the first of June. It was quite surprising that both Early Autumn and Tropicana, maturity between 55 to 60 days, had 100% bolting. Initially, the trial was to determine the tolerance or resistance to the Turnip Mosaic Virus. During this period, no symptom of the virus was found on all of the cultivars. As mentioned above, the summer trial was to determine the tolerance or resistance to the Bacterial Buttrot. Because of the earlier field findings of "Gomasho" and tip burn, these two disorders were included in the data. Some explanations for Table 1. The total heads harvested included heads afflicted with "Gomasho and tip-burns. To determine the incidence of the tip-burn, appropriately 50% of the harvested heads, at that particular harvest, were cut open. The column for Tip-burn in Table 1 indicates that for Early Top, a total of 9 out of 13 heads were afflicted with internal tip-burn.
Of the early maturing cultivars (55 to 60 daye ) WR 55 had the highest incidence of the Bacterial Butt-rot and also a high incidence of the tipburn. Although Gomasho was reported to be found on China Express and Hi-Mark in the field, only Hi-Mark and WR 70 had shown the Gomasho symptom in the trial. The incidence of the tip burn could be contributed to Born deficiency as well as calcium deficiency and lack of moisture. Other symptom of Boron deficiency is the midribs crack which later turns brown. It is was found that Born when applied in exceas can reduce yields. It is recommended that Boron as Borate be applied at the rate of 4-5 pounds per acre. It is difficult to recommend the cultivar to plant in Kula as indicated in Table 1. Somo of tho cultivars are highly resistant to the Bacterial But-rot but is very susceptible to the tip-burn or Gomasho. My recommendation is to try some of the cultivars on your farm and evaluate them. The conditions on your farm might be a little different from the Kula Ag-park Station and also the cultural method used in the production of the cultlvars. Table 1: Yield and disease data of the chinese cabbage variety trial at the kula ag park station, april 5 to july 20, 1989 days to Total heads total avg wt. butt rot bolting non heading mosaic gomasho tip burn* cultivar maturity harvest ed wt(lbs) per head no/% no/% no/% no/% no/% no. Dancer 40 - - - - 30/I00 - - - - Tropical Shot 40 - - - - 30/I00 - - - - Saladeer 45 - - - - 30/100 - - - - Sonnet 45 - - - - 30/I00 - - - - Trpocial Quick 45 - - - - 30/I00 - - - - Tropical Rapid 45 - - - - 30/100 - - - - Tropical Delight 55 - - - - 30/I00 - - - - Tropical Pride 55 - - - - 30/I00 - - - - Early Autumn 55 - - - - 30/I00 - - - - WR 55 55 21 63.5 3.0 3/I0.0 3/10.0 3/10.0 - - 11/1 Blue 57 27 85.5 3.2 I/3.30-2/6.70 - - 8/14
Early Top 60 28 I00.4 3.6 I/3.30-1/3.30 - - 9/13 China Express 60 28 89.2 3.2 2/6.70 - - - - 1/4 Tropicana 60 - - - - 30/I00 - - - - Rumba 60 14 41.3 2.9-6/20.0 I0/33.3 - - 6/6 WR 60 60 26 87.0 3.4 - - 4/13.3 - - 11/1 WR 60 green 60 27 75.5 2.8 - - 3/10.0 - - 12/I Hero 63 27 75.0 2.8 I/3.30-2/6.70 - - 10/1 Tango 67 29 95.4 3.3 I/3.30 - - - - 8/14 WR 70 67 27 89.2 3.3 I/3.30-2/6.70-1/3.30 7/9 WR 65 65 21 87.5 4.2 4/13.3 - - - 2/2 China Pride 70 30 107.9 3.6-2/6.70 1/3.30 - - 2/4 China King 70 25 103.5 4.1 2/6.70 16/53.3 - - - 2/3 Green Rocket ** 70 9 26.0 2.9 5/I6.7 - - - - 6/6 Spring Triumph 75 27 90.8 3.4 3/I0.0-21/70.0 - - - WR crusade 80 9 25.8 2.9 - - - - - - Winter giant 85 4 14.4 3.6 4/I3.8 1/3.30 1/3.30 - - 20/2 Winter Champion 100 22 75.9 3.4 2/6.70-6/20.0 - - 4/4 Hi Mark? 30 77.2 2.6 - - - - 4/13.3 2/14 * Both external and internal tip burn. Figure on the left ofthe slash mark (/) indicates the number of head affected with the tip burn. Figure on the right of the slash mark (/) indicated the total number of heads analyzed for tip burn. ** Michihili type. ***** LITERATURE Boron Deficiency,Its Prevention and Cure is a 43 paged, colored booklet describing the various symptoms of Boron deficiency in several horticultural crops including vegetables. For a copy of this publication, write to US Borax & Chemical Corporation 3075 Wilshire blvd. los angelos CA 90010
***** UP DATE OF UH CUCUMBER LANI AND MILO Dr. Terry Sekioka, hybridizer of both Lani and Milo, reported that both cultivars are resistant to the Watermelon Mosaic Virus 2 (WMV-2) and the Cucumber Mosaic Virus (CMV). He and Dr. X. Takeda are working to incorporate Zucchine Yellows Mosaic Viru8 (ZYMV) resistance into the above. He is having difficulty in developing a resistant variety to the Zucchine Yellows because lines developed by crossing to the ZYMV parent have bitter fruits. He further reported that the parents of lani" are "79-22 and "75A-l. 79-22 is an inbred line of a cross between "Sooyow and Lehua. "Sooyow" was selected because of its crisp fruit and tolerance to WMV-2. Lehua was chosen for CMV and WMV-2 resistance and tolerance to powdery mildew. 75A-l-l" is an inbred line from the cross between "Tokyo Long Greenn and Lehua "Tokyo Long Green" has very crisp fruits and CMV resistance. The parent of "Hilo are "79 25 and 75A-l-l. "79-25 is a sibling of "79-22 and "75A-l is a sibling of 75A-l-l Although both hybrids are closely related (in human terms), they are quite different in yielding potential, fruit traits and vine characters. The two most common viruses of cucurbits that were reported by Drs. Cho and Ullman are the Watermelon Mosaic Virus-l and the Zucchine Yellow Mosaic Virus. ***** PURPLE IS IN A purple asparagus has appeared in the specialty market. Brian Benson, developer of this asparagus
, obtained material from Italy to develop this hybrid. (American Vegetable Grower, June 1989) ***** ************** SWEET POTATO The Internal CorK Disease is caused by the Sweet Potato Feathery Mosaic virus. This virus also causes root necrosis. (Plant Disease, Vol. 73, No. 6) ***** CAULIFLOWER A bright orange cauliflower was developed by Cornell University researchers that equals white head in taste but has a longer shelf life. It has a higher carotene content which is a plus because of health food fad of today. (American Vegetable Growers, Dec. 1988) FUNGI - FUTURE INSECTICIDES Chemical compounds produced by a Penicillin species gave excellent control of armyworm and earworm. Armyworm fed with Peniterm A at 25 ppm grew half the size of larvae on control diet and earworm reacted the same but to only 25 ppb. Roseotoxin B fed at 25 ppm killed all armyworm and more than 30% of the earworm in 2 days. (AG Consultant, Aug. 1988) ***** SWEET POTATO WHITEFLY UP-DATE
Pat Conant, State Entomologist, reported that a survey conducted on Maui did not find any Sweet Potato Whitefly. His department will continue to survey for this insect on Maui. As I had reported in one of the Vegetable Notes, this whitefly is known to be a vector of several vegetablq viruses. Ted M. Hori County Extenston Agent Agriculture Program