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Diflufenican, a pre- and early post-emergence herbicide, was found to be highly active against a wide range of weeds at application rates of 50–250 g ha-1. Studies on the mode of selectivity with [14C]diflufenican have demonstrated that selectivity between cereal crops and selected weed species is primarily due to differential uptake and indirectly to translocation; ‘depth protection’ appears to be the major reason for selectivity of soil-applied diflufenican. 相似文献
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Phytophthora root rot, caused byPhytophthora cinnamomi Rands, is the most important disease of avocado (Persea americana Miller). In an attempt to identify root rot-resistant rootstocks that could ultimately be used under conditions in southern
Florida, we screened open-pollinated progeny of avocado from the National Germplasm Repository in Miami. From 1996 to 1998,
a total of 2,355 seedlings from 51 accessions were examined in potting mix artificially infested withP. cinnamomi. Most seedlings developed severe root rot, but tolerance was observed in some families (i.e., progeny of certain accessions). Although the most susceptible families developed mean disease ratings of up to 97% root
necrosis, mean ratings for the most tolerant families were less than 60%. There was also a strong relationship between the
racial background of the female parent and the tolerance of seedlings. Seedlings of the West Indian race and hybrids between
it and the Guatemalan race were significantly more tolerant than those from other parents (P< 0.05). Individuals in several
families developed < 50% root necrosis, the arbitrary standard of tolerance in this study. Twelve families accounted for 82%
(188 of 229) of the tolerant seedlings, and only two of these did not have a West Indian or Guatemalan × West Indian pedigree.
Broad-sense heritability for PRR tolerance was 0.45. This is the first report on the inheritance of PRR tolerance in avocado
and on the influence of genotype and racial pedigree under controlled conditions. 相似文献
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Twelve 9-week-old calves were divided into four groups; two groups were maintained helminth-free as controls and the other groups were given Ostertagia ostertagi infective-stage larvae (L3) orally. One group received 100,000 L3 as a single inoculum and the other group received L3 in increasing dosages at weekly intervals for 8 consecutive weeks. The blastogenic responses to concanavalin A (Con A), phytohemagglutinin (PHA), and a soluble larval antigen from O. ostertagi (SLA) of peripheral blood lymphocytes were evaluated using tritiated thymidine incorporation into DNA as a measure of blastogenesis. The responses to Con A of all infected calves were significantly depressed while the responses to PHA were not. SLA, at concentrations of 4 micrograms ml-1 and above, caused blastogenic activity in lymphocytes from uninfected calves. Using SLA at 1 microgram ml-1 in lymphocyte cultures supplemented with autologous serum, an antigen-induced blastogenic response was detected in calves receiving serial inoculations of L3. 相似文献
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V S Panangala T B Haynes R D Schultz A Mitra 《Veterinary immunology and immunopathology》1986,13(1-2):71-84
Immunomodulation with killed Propionibacterium acnes was attempted in guinea pigs simultaneously vaccinated with Brucella abortus strain 19. Two groups, each comprised of 9 guinea pigs, were injected by different routes (s.c. and or i.v.) with 1.4 mg of P. acnes and 5 X 10(8) CFU of B. abortus, S-19, while 3 other groups each received either P. acnes, B. abortus S-19, or saline (s.c.). The antibody titers to B. abortus measured at 6, 10 and 14 weeks after vaccination indicated no significant (P less than 0.01) response in the 2 groups immunopotentiated with P. acnes concurrent with B. abortus S-19 vaccination. The delayed hypersensitivity response to 3 Brucella antigens conducted 8 weeks after immunization did not show a significant difference between the B. abortus S-19 vaccinated group compared with the 2 groups immunopotentiated and vaccinated. However, the proliferative response of lymphocytes to the B. abortus soluble antigen diluted 1:100 indicated significantly enhanced blastogenesis in the (s.c.) immunopotentiated and immunized guinea pigs compared with the B. abortus S-19 vaccinated group. A slightly enhanced response was also observed in the group immunopotentiated (i.v.) and vaccinated (s.c.). The guinea pigs were challenged with B. abortus strain 2308 and necropsied 4 weeks later. The mean splenic CFU of the Brucella in the group immunopotentiated (i.v.) and vaccinated (s.c.) was significantly decreased when compared with the guinea pigs vaccinated with B. abortus S-19 alone. These findings indicated that P. acnes administered simultaneously with B. abortus S-19 vaccine was able to augment the immune response in guinea pigs. Immunomodulation as evidenced by enhanced clearance of B. abortus from the spleens of immunopotentiated animals was presumably brought about by activated macrophages or a T-cell mediated cytolytic mechanism or both. 相似文献
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A 4-month-old Thoroughbred filly presented for abdominal pain was diagnosed with a T-shaped malformation of the ventral colon at exploratory laparotomy. Following resection and anastomosis of the large colon, no further episodes of abdominal pain occurred during a 12-month follow-up. Acute dehiscence of the linea alba occurred as a complication of the initial laparotomy, but was successfully managed following additional surgical repair. T-shaped malformation of the ventral colon has not previously been reported and is considered a congenital malformation of mesocolon formation. 相似文献
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