scholarly journals Stemphylium botryosum Pathogenic on Spinach Seed Crops in Washington

Plant Disease ◽  
2001 ◽  
Vol 85 (8) ◽  
pp. 920-920 ◽  
Author(s):  
L. J. du Toit ◽  
M. L. Derie
Keyword(s):  
Leaf Tissue ◽  
Tween 80 ◽  
Stemphylium Botryosum ◽  
The Third ◽  
Plastic Bags ◽  
Spinacea Oleracea ◽  
Foliar Pathogen ◽  
Symptomatic Leaf ◽  
Western Washington ◽  
Seed Crops

In September 2000, symptoms typical of leaf spot caused by Cladosporium variabile were observed on a spinach (Spinacea oleracea L.) seed crop in western Washington. Dry, bleached spots (1 to 20 mm) were most abundant on lower leaves. Two isolates of C. variabile and three isolates of Stemphylium were recovered by plating surface-sterilized (0.1% sodium hypochlorite) sections of symptomatic leaf tissue onto water agar and acidified potato dextrose agar (PDA). Transfers of each isolate were made to PDA, and cultures were kept at 24 ± 2°C on a lab bench (natural day/night cycle) for 10 to 14 days. Spore suspensions (105/ml) of the isolates of C. variabile were prepared in a 0.01% solution of Tween 80. Isolates of Stemphylium produced few spores, so mycelial suspensions (105 fragments/ml) were prepared. Five 8-week-old seedlings of each of the cultivars Winter Bloomsdale and Ozarka II were inoculated per fungal isolate by atomizing the inoculum onto each seedling until all leaves were covered with a thin film of droplets (4 to 5 ml of inoculum per seedling). Plants were enclosed in plastic bags on a greenhouse bench (24 ± 3°C) for 72 h (8 h/16 h day/night). Symptoms developed within 80 h of inoculation for both isolates of C. variabile and two isolates of Stemphylium. Small (1 to 2 mm) sunken spots turned white 24 to 48 h later and became dry and bleached. Lesions caused by isolates of Stemphylium enlarged and coalesced more rapidly than lesions caused by C. variabile, and were more irregular and usually not delimited by the thin brown margin typical of lesions caused by C. variabile. The differences in symptoms were consistent on both spinach cultivars. Symptoms were not observed on non-inoculated control plants nor on plants inoculated with the third isolate of Stemphylium. C. variabile and Stemphylium were reisolated from symptomatic leaf tissue. Colony morphology, conidiophores, and conidia of the pathogenic Stemphylium isolates were similar to those of pathogenic isolates of Stemphylium botryosum obtained from spinach plants in California (2). This is the first report of S. botryosum as a foliar pathogen of spinach seed crops in Washington. Although Correll et al. (1) noted Stemphylium to be damaging on mature spinach plants grown for seed production, S. botryosum may not have been diagnosed previously on spinach seed crops in Washington because of the similarity of symptoms caused by S. botryosum and C. variabile. S. botryosum was recently reported as a foliar pathogen of spinach in California (2). References: (1) J. C. Correll et al. Plant Dis. 78:653, 1994. (2) S. T. Koike et al. Plant Dis. 85:126, 2001.

scholarly journals Evidence that Cercospora carotae Causes Leaf Spot on Carrot in Western Washington

Plant Disease ◽  
2001 ◽  
Vol 85 (5) ◽  
pp. 559-559
Author(s):  
D. A. Inglis ◽  
M. L. Derie ◽  
K. C. Volker
Keyword(s):  
Leaf Spot ◽  
Leaf Tissue ◽  
Tween 80 ◽  
The United States ◽  
Cercospora Leaf Spot ◽  
Disease Symptoms ◽  
Daucus Carota L ◽  
Clear Plastic ◽  
Western Washington ◽  
Cercospora Carotae

During 1999, a leaf spot on carrot (Daucus carota L. subsp. sativus [Hoffm.] Arcang.) was observed on nearly every plant in a 20-ha field of carrots (cv. Red Chantenay) grown for processing in western Washington. Circular to elongate, light brown lesions surrounded by chlorosis were present on leaflet margins and petioles of affected plants. Conidia of Cercospora carotae (Pass.) Solheim were present in the lesions. Small pieces of surface-sterilized leaf tissue were placed onto potato dextrose agar plates and incubated at room temperature to obtain fungal isolates. Koch's postulates were completed by atomizing the upper and lower leaves of carrot seedlings at the three to four leaf stage with sterile water or C. carotae at 1.0 × 104 conidia/ml in sterile 0.01% Tween 80. Treatments were replicated five times using single plants. The plants were bagged in clear plastic and placed in a greenhouse at 25°C for 72 h. Disease symptoms developed within 10 days as light brown lesions on leaflet margins and petioles, and were similar to those found in the field. The fungus was reisolated as described above. Symptoms did not develop in control plants sprayed with water. Farr et al. (1) report that C. carotae occurs in several states but not Washington, and Shaw (2) lists C. carotae only from British Columbia and Oregon. To our knowledge, this is the first report of Cercospora leaf spot on carrot in Washington. References: (1) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN. (2) C. G. Shaw. W.S.U. Agric. Exp. Sta. Bull. 765, 1969.

scholarly journals Stem Canker of Cabbage Seed Stalks Caused by Botrytis cinerea in Western Washington

Plant Disease ◽  
2001 ◽  
Vol 85 (5) ◽  
pp. 559-559
Author(s):  
D. Inglis ◽  
M. Derie ◽  
T. Hsiang
Keyword(s):  
Brassica Oleracea ◽  
Botrytis Cinerea ◽  
Mechanical Damage ◽  
Tween 80 ◽  
Stem Canker ◽  
The United States ◽  
Gray Mold ◽  
Freezing Injury ◽  
Razor Blade ◽  
Western Washington

Stem cankers were observed during 1998 on bolting stalks of cabbage (Brassica oleracea var. capitata L.) in seed production fields in western Washington. In 1999, approximately 4 ha of cabbage hybrid 'Wk 121, was severely affected. Lesions occurred at the base of seed stalks after they emerged from heads of plants overwintered in the field, or on flower branches and seed-bearing stalks that developed during the growing season. Lesions girdled a branch or stalk, and killed or weakened it so that it broke during pod fill. Isolates of Botrytis cinerea Pers.:Fr. were obtained by plating spores from lesions onto potato dextrose agar. To confirm pathogenicity, stems of 12-day-old seedlings of ‘Wk 121’ were scraped with a razor blade or left intact, atomized with sterile 0.01 % Tween 80 or a suspension of Botrytis cinerea at 1.0 × 106 conidia/ml, and kept at 20°C in a dew chamber in plastic bags. The fungus was reisolated from small lesions on wounded stems inoculated with B. cinerea after 3 days. No lesions developed on non-wounded or wounded control plants. B. cinerea is reported to cause storage rot of cabbage (2) and gray mold on Brassica oleracea L. (cabbage, kale, kohlrabi, wild cabbage) in Washington (1) but not stem canker. This new seed crop disease may be the result of predisposition to infection by freezing injury or mechanical damage on a highly susceptible cultivar grown under cool, wet weather. References: (1) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society. St. Paul, MN. (2) O. C. Yoder and M. L. Whalen. Can. J. Bot. 53:691, 1975.

scholarly journals MAKNA IDIOMATIS DALAM MAJALAH SUARA PENDIDIKAN EDISI OKTOBER-NOVEMBER 2018

2019 ◽  
Vol 7 (4) ◽  
pp. 38
Author(s):  
Irwansyah Irwansyah
Keyword(s):  
Research Method ◽  
Research Data ◽  
Written Language ◽  
Data Sources ◽  
The Third ◽  
Original Meaning ◽  
Plastic Bags ◽  
The City ◽  
Descriptive Qualitative

The researcher discusses the meaning contained in the magazine because language users often do not understand the meaning contained in written language, namely idioms. The reader is often difficult to understand because the meaning is no different with the original meaning o concept that embodies. Researchers focus the research by using three types of idioms, namely the meaning of the idiomatic based on the occurrences of idioms in the form of the mention of a part of the whole assumption, the meaning of the idiomatic based on the occurrences of idioms in the form of the mention of the material, and the meaning of idiomatic based on the type of idiom in the form of the expression. Research conducted discusses the word as material for analysis so that the required description of that detail. The research method used is descriptive qualitative because in accordance with the discussion and data sources that will be examined. According to the results of the analysis of research data about the meaning of idiomatic in Sounds magazine Education edition October-November 2018 that has been done found some kind of meaning idiomatic. The data is obtained based on the three focus that have been formulated in the focus of research. The data was found in accordance with the three focus of research, the first data are the city of santri, onde-onde city and samurai country. The second data are Plastic bags, banknotes and coins. And the third data are Baby, rising level and souvenirs.

scholarly journals RESPONSE OF CATHARANTHUS ROSEUS “GRAPE COOLER” TO MEDIA AND FERTILIZER SOLUTION CONCENTRATION USING SUBIRRIGATION

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 687c-687
Author(s):  
G.C. Elliott ◽  
R.J. McAvoy ◽  
M. Abbott
Keyword(s):  
Electrical Conductivity ◽  
Catharanthus Roseus ◽  
Leaf Tissue ◽  
Solution Concentration ◽  
Essential Elements ◽  
Fresh Weight ◽  
The Third ◽  
Saturated Media ◽  
Final Harvest ◽  
Fertilizer Solution

Seedlings of Catharanthus roseus “Grape Cooler” was transplanted to cell packs of media: peat-vermiculite-perlite (MM220), peat-hydrophilic rockwool (ABS), and peat-hydrophobic rockwool (REP) and grown in subirrigation trays using 20N-4.4P-17K fertilizer at 50, 150 or 250 ppm N applied at each irrigation. Shoots of four plants in each of two replications were harvested 2, 3, 4 and 5 after transplant. Leaf samples from the third harvest were analyzed for essential elements. Electrical conductivity (EC) was measured in saturated media extracts at each harvest. Significant media by fertilizer interactions were obtained for fresh weight and leaf area at the final harvest. Greatest growth was obtained with 50 ppm N in ABS, but with 150 ppm N in MM 220 and REP. In tehse, growth was similar at 50 and 150 ppm N, but less growth REP than MM220 at 250 ppm. More growth was produced with ABS at 50 ppm N, but less at 150 or 250 ppm N. Leaf tissue N increased 38.5 to 54.5 mg g-1 dry wt. as fertilized increased 50 to 150 ppm, while other nutrients were not significantly affected. Media EC increased with time and fertilizer concentration, with EC in all media fertilized with 250 ppm N exceeding 4.5 dS m-1 at the final harvest.

scholarly journals Xanthomonas Blight of Onion in South Africa

Plant Disease ◽  
2001 ◽  
Vol 85 (4) ◽  
pp. 442-442 ◽  
Author(s):  
J. J. Serfontein
Keyword(s):  
South Africa ◽  
Tween 80 ◽  
Pathogenicity Test ◽  
Foliar Blight ◽  
Foliar Symptoms ◽  
Plastic Bags ◽  
Overhead Irrigation ◽  
Allium Cepa L ◽  
Pure Cultures ◽  
Biolog Gn

During April 1999, a foliar blight of onion (Allium cepa L. ‘Granex 33’) was reported in an early commercial planting under center pivot irrigation in the Limpopo Valley of the Northern Province of South Africa. Regular fungicide sprays failed to inhibit the progress of the disease. Foliar symptoms started as water-soaked lesions that elongated and turned chlorotic followed by tissue collapse in some leaves. Leaves often collapsed at the point of infection. Bulb size was severely reduced and premature leaf death caused irregular maturation and bulb size in the field. The symptoms were similar to those of Xanthomonas blight, described on the same cultivar in Hawaii (1). Microscopic examination of hand cut sections trough lesion margins showed bacterial streaming. Isolation on semi-selective diagnostic milk Tween agar (2) yielded almost pure cultures of a typical xanthomonad. The mucoid, yellow pigmented bacterium was rod shaped, gram negative, catalase positive, oxidase negative, utilized glucose oxidatively, and was lypolytic (Tween 80), proteolytic (skimmed milk), and amolytic. Biolog GN Microplate profiles as read by the MicroLog database release 3.50 (Biolog, Hayward, CA) were similar to those of a pathovar (similarity indices of 0.29 to 0.71). Symptoms were successfully reproduced on glasshouse grown Granex 33 seedlings at the five-leaf stage by spray and syringe inoculations (1) and the pathogen reisolated as described above. Ten seedlings were used in the pathogenicity test, of which five served as controls. After inoculation, seedlings were covered overnight with plastic bags, after which bags were removed and seedlings grown in the greenhouse at 24 to 30°C and natural light until symptom development. Attempts to isolate the pathogen from the seed lot used to plant the affected field were unsuccessful. The disease re-occurred in early plantings of Granex 33 on the same farm in April 2000 toward the end of an unusually wet summer rainy season. Damage caused by the disease was so severe in one early planting that it was plowed under. High temperatures and humid conditions combined with overhead irrigation could have enhanced disease development and spread during the early growth of the crop. No further spread was observed during cooler and drier weather later in the season. References: (1) A. M. Alvarez et al. Phytopathology 68:1132, 1978. (2) T. Goszczynska and J. J. Serfontein. J. Microbiol. Methods 32:65, 1998.

scholarly journals First Report of Alternaria panax Causing Leaf Spot of Aralia cordata in Japan

Plant Disease ◽  
2009 ◽  
Vol 93 (11) ◽  
pp. 1215-1215
Author(s):  
M. Zhang ◽  
T. Tsukiboshi ◽  
I. Okabe
Keyword(s):  
Herbal Medicines ◽  
Central Area ◽  
Leaf Tissue ◽  
Plant Diseases ◽  
Korean Society ◽  
First Report ◽  
Aralia Cordata ◽  
Leaf Spots ◽  
Plastic Bags ◽  
Alternaria Panax

Udo, Aralia cordata Thumb, Araliaceae, is a traditional Japanese perennial vegetable and used in Chinese herbal medicines. During the last 10 days of July 2008, before the period of flower, leaf spots were observed on udo growing under pine trees in Nasushiobara, Tochigi, Japan. Leaf spots affected more than 40% of the plants. Early symptoms appeared as small, round or irregular, water-soaked, dark brown lesions on the leaves. These areas expanded to 15 to 30 mm in diameter, were irregular and pale brown in the central area and the margin of the lesions were water soaked and dark brown. Later, some lesions coalesced. In continuously wet or humid conditions, conidiophores with conidia appeared on the surface of leaf spots. Conidiophores were medium brown and simple (approximately 70 to 160 × 6 to 8 μm). Well-developed conidia were long-obclavate, base obtuse, straight, yellowish brown, smooth walled, with six to nine transverse septa and three to five longitudinal or oblique septa, constricted at some main septa, some cells easily swelled, conidium body was 72 to 100 × 19 to 34 μm, and the rostra extension was 40 to 90 × 4 to 5 μm. The pathogen was identified as Alternaria panax on the basis of the morphology and sequence of ITS1-5.8s-ITS2 of rDNA. The sequence (GenBank Accession No. FJ607183) exactly matched the sequences of two A. panax (e.g., GenBank Accession Nos. AY898639 and AY898640) (2–4). The fungus was isolated on V8 agar from a single conidium found on symptomatic leaf tissue. Colonies of A. panax were gray-to-black and did not easily produce conidia on the agar. Koch's postulates were performed with the leaves of three branches on a field plant of Aralia cordata. Leaves were inoculated with a mycelial plug harvested from the periphery of a 7-day-old colony; an equal number of leaves on the same plant inoculated with plugs of V8 medium served as the control. All test leaves were covered with plastic bags for 24 h to maintain high relative humidity and incubated at a natural temperature (approximately 24 to 28°C). After 7 days, all inoculated leaves showed symptoms identical to those observed in natural conditions, whereas the controls remained symptom free. Reisolation of the fungus from lesions on inoculated leaves confirmed that the causal agent was A. panax. This species has been previously reported on Aralia cordata in Korea (1). To our knowledge, this is the first report of leaf spots caused by A. panax on Aralia cordata in Japan. References: (1) W. D. Cho and H. D. Shin. List of Plant Diseases in Korea. 4th ed. Korean Society of Plant Pathology, 2004. (2) E. G. Simmons. Mycotaxon 14:17, 1982. (3) E. G. Simmons. Alternaria: An Identification Manual. CBS Fungal Biodiversity Centre, Utrecht, the Netherlands, 2007. (4) T. Y. Zhang et al. Flora Fungorum Sinicorum: Alternaria. Vol. 16. Science Press (in Chinese), Beijing, 2003.

scholarly journals Detection of Ramularia collo-cygni DMI- and SDHI-resistant field populations in Austria and the effect of fungicides on the population and genetic diversity

2021 ◽  
Author(s):  
Thomas Assinger ◽  
James Fountaine ◽  
Stefano Torriani ◽  
Salvatore Accardo ◽  
Regula Bernhard-Frey ◽  
...  
Keyword(s):  
Mutation Frequency ◽  
Field Survey ◽  
High Dose ◽  
Dose Rates ◽  
The Third ◽  
Leaf Spots ◽  
Foliar Pathogen ◽  
Fungicide Mixtures ◽  
The Eu ◽  
Current Resistance

AbstractWinter barley (Hordeum vulgare L.) is the third most cultivated crop after corn and wheat in Austria but one of the most challenging for disease control. The foliar pathogen Ramularia collo-cygni B. Sutton and J.M. Waller, causing Ramularia leaf spots (RLS), is one of the most important diseases in barley. In the recent years, control has only been achieved using fungicide mixtures including the multi-site inhibitor chlorothalonil, however this compound is totally banned in the EU. The objective of this study was to assess fungicide dose-rates and spray mixtures for RLS control. Furthermore, a field monitoring within the main barley growing areas of Austria was carried out, to analyse the current resistance situation to DMI and SDHI fungicides, which are still the backbone in RLS control. The results indicate that only the mixture with chlorothalonil achieved a good RLS control. Prothioconazole or benzovindiflupyr (alone or additively) decrease the severity of RLS but increase the local frequency of Cyp51 and sdhC mutations, especially the high dose rates. Based on a low Cyp51 mutation frequency of 16% in untreated control this frequency increased over 3.8 times following an application with 300 g ha−1 prothioconazole. The cumulative-sdhC mutations were even more increased after an application with benzovindiflupyr. This study showed that Ramularia collo-cygni is present in 91% of barley fields presented in this field survey. Widespread use of chlorothalonil fungicide maintained a low to moderate mutation frequency (Cyp51-I325T, Cyp51-I328L, sdhC-H146R and sdhC-H153R) in Austrian barley regions with no increase between 2017 and 2019.

scholarly journals First report of anthracnose caused by Colletotrichum fructicola on tea in Taiwan

Plant Disease ◽  
2020 ◽  
Author(s):  
Shiou-Ruei Lin ◽  
Si-Ying Yu ◽  
Tsai-De Chang ◽  
Yi-Jia Lin ◽  
Chen-Jie Wen ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Intergenic Spacer ◽  
Leaf Tissue ◽  
Nuclear Ribosomal Dna ◽  
Conidial Suspension ◽  
Water Control ◽  
First Report ◽  
Colletotrichum Fructicola ◽  
Symptomatic Leaf ◽  
Tea Plants

Tea (Camellia sinensis (L.) O. Kuntze) is a very popular beverage and cash crop that is widely cultivated in tropical and subtropical areas. In November 2017, diseased tea plants that exhibiting brown blight disease were observed in Guanxi Township of Hsinchu County in Taiwan. In the plantation,15% of tea trees (about 4000 plants) had an average of 20% of the leaves with at least one lesion. The symptoms began as small, water-soaked lesions on young leaves and twigs and later became larger, dark brown, necrotic lesions of 1 to 3 cm in diameter on leaves and 2 to 5 cm in length on twigs. Symptomatic leaf tissue (1 cm2) from five samples per sample) was surface sterilized with 1% NaClO (from commercial bleach, Clorox) for 1 min, washed with sterilized water 3 times, plated onto potato dextrose agar (PDA), and incubated under 12h/12h cycles of light and darkness at 25°C until sporulation to determine the causal agent. A fungus was consistently isolated from symptomatic leaf samples (80% isolation rate). The fungus initially produced white-to-gray fluffy aerial hyphae, which subsequently exhibited dark pigmentation. Acervuli and setae were absent. The conidia were hyaline, aseptate, smooth-walled, and cylindrical with obtuse to slightly rounded ends, with sizes of 12.10 to 16.02 × 3.58 to 4.91 (average 13.77 × 4.05, n = 30) μm. The majority had two rounded guttules. The appressoria were brown to dark brown, ovoid and slightly obtuse at the tip in shape, had lengths ranging from 3.59 to 10.31 μm (with an average of 7.18 μm, n = 30), and had diameters of 3.14 to 6.43 μm (with an average of 5.10 μm, n = 30). Morphological characteristics matched the descriptions of Colletotrichum fructicola (Liu et al. 2015; Fuentes-Aragón et al. 2018). The internal transcribed spacer of nuclear ribosomal DNA (ITS), actin (ACT), chitin synthase (CHS-1), and Apn2-Mat1-2 intergenic spacer and partial mating-type Mat1-2 gene (ApMAT) sequences of the isolates were obtained to confirm this identification. The sequences showed close identity with those of C. fructicola ex-type cultures ICMP18581 and CBS 130416 (Weir et al. 2012) of 99.65% for the ITS (JX010165), 99.29% for the ACT (JX009501), and 100.00% for the CHS-1 (JX009866), as well as close identity with the other ex-type culture LF506 (Liu et al. 2015) of 99.59% for the ApMat (KJ954567), supporting the isolate’s identification as C. fructicola. The sequences were deposited in GenBank, with the following accession Nos.: MN608177 (ITS), MN393175 (ACT), MT087546 (CHS-1), and MT087542 (ApMAT). Based on morphology and DNA sequence analysis, the associated fungus was identified as C. fructicola. Pathogenicity tests were performed next according to the procedures described in Chen et al. (2017). Healthy leaves on tea plants (Ca. sinensis ‘Chin-shin Oolong’) were wounded by pinpricking in the middle of each counterpart and inoculated with conidial suspension (1 × 107 conidia/ml, 10 μl). Both non-wounded and wounded healthy leaves were inoculated with the conidial suspension and sterile distilled water (a water control). The tea plants were covered with plastic bags to maintain high relative humidity for two days. One week after inoculation, anthracnose was observed on 40% of inoculated leaves, whereas all the control leaves remained healthy. The fungus was re-isolated from the diseased plants, and identified as C. fructicola by resequencing of the four genes. To the best of our knowledge, this is the first report of anthracnose caused by C. fructicola on tea in Taiwan although the pathogen has been present in China and Indonesia (Wang et al. 2016; Shi et al. 2017; Farr and Rossman, 2020).

Chlorophyll fluorescence for rapid detection of propanil-resistant barnyardgrass (Echinochloa crus-galli)

Weed Science ◽  
1998 ◽  
Vol 46 (2) ◽  
pp. 163-169 ◽  
Author(s):  
Jason K. Norsworthy ◽  
Ronald E. Talbert ◽  
Robert E. Hoagland
Keyword(s):  
Chlorophyll Fluorescence ◽  
Incubation Temperature ◽  
Recovery Period ◽  
Screening Method ◽  
Leaf Tissue ◽  
Activity Levels ◽  
Photosynthesis Inhibition ◽  
Plastic Bags ◽  
Time Space ◽  
Aryl Acylamidase

Repeated use of propanil to control barnyardgrass (BYG) and other weeds in rice has led to the development of propanil-resistant barnyardgrass (R-BYG). R-BYG possesses elevated aryl acylamidase activity levels, which cause rapid metabolism of propanil analogous to propanil degradation in rice. The current screening method for determining propanil resistance in BYG requires about 10 mo. The present study examined the use of chlorophyll fluorescence as a more rapid method to identify propanil resistance in BYG soon after it is suspected. Chlorophyll fluorescence data from excised BYG leaf tissue (R-BYG and susceptible-BYG [S-BYG]; 13- to 41-d-old) exposed to 100 μM propanil for 2 h indicated a 95 to 100% inhibition of electron transport (photosynthesis inhibition) in both R- and S-BYG. However, when incubated in water in the dark for 22 h after the initial 2-h treatment, metabolism in R-BYG was sufficient to reduce levels of absorbed propanil and facilitate recovery. Lack of metabolism of propanil prevented recovery in S-BYG, thus allowing the two biotypes to be distinguished easily by the chlorophyll fluorescence assay. Further studies using this 2-h exposure to 100 μM propanil followed by a 22-h recovery period evaluated several assay parameters. A longer recovery time and the effects of various propanil concentrations were also evaluated. A herbicide dose-response curve showed the greatest difference in photosynthesis inhibition for both biotypes at about 100 μM propanil, but both biotypes were inhibited > 95% when treated with 400 μM propanil. Inhibition of photosynthesis in both biotypes was greatest when the recovery incubation temperature was 35 C compared to 20, 25, and 30 C. Fluorescence data from harvested tissue stored moist in plastic bags at 23 C (to simulate shipment) showed that biotypes could be differentiated even when received as late as 4 d after harvest. Thus, samples can be harvested from the field soon after propanil failure and resistance or susceptibility to propanil determined after only a few days. This technique can greatly reduce the time, space, and labor currently required to determine propanil resistance in BYG.

Chemical Manipulation of Grass Seed Crops

1985 ◽  
Vol 2 ◽  
pp. 9-14
Author(s):  
J.G. Hampton ◽  
T.G.A. Clemence ◽  
B.L. Mccloy
Keyword(s):  
Seed Yield ◽  
Perennial Ryegrass ◽  
Leaf Tissue ◽  
Yield Potential ◽  
Seed Abortion ◽  
Growth Retardants ◽  
Grass Seed ◽  
Poor Seed ◽  
Seed Crops ◽  
Seed Yields

The seed yield potential established at anthesis in grass seed crops is usually 5-10 times greater than actual seed yields realised at harvest. Losses in seed yield between anthesis and harvest result primarily from the death of fertile tillers and poor seed site utilisation. Lodging has been identified as one of the most important factors reducing seed yields, and the use of growth retardants has significantly increased seed yield in perennial ryegrass and tall fescue. The effects of the growth retardant paclobutrazol on the growth, development and seed yield of perennial ryegrass (Lolium perenne) are presented and discussed. Little is known of the effects of leaf and stem diseases on grass seed yields. Recent research has found that fungicide application can substantially increase seed yield in perennial ryegrass through delaying senescence of leaf tissue. Increased leaf area duration is associated with a reduction in seed abortion, resulting in more seeds per spikelet at harvest. The possibilities for fungicide use in the crop are discussed. Keywords: Seed production, grasses, fertile tillers, seed abortion, growth retardants, paclobutrazol, fungicide, senescence.

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