The effects of autumn closing date on sward leaf area index and herbage mass during the winter period

The provision of grass for early spring grazing in Ireland is critical for spring calving grass‐based milk production systems. This experiment investigated the effect of a range of autumn closing dates (CD), on herbage mass (kg DM ha^?1), leaf area index (LAI) and tiller density (m^?2) during winter and early spring. Thirty‐six grazing paddocks, closed from 23 September to 1 December 2007, were grouped to create five mean CD treatments – 29 September, 13 October, 27 October, 10 November, 24 November. Herbage mass, tiller density and LAI were measured every 3 weeks from 28 November 2007 to 20 February 2008; additionally, herbage mass was measured prior to initial spring grazing and tiller density was measured intermittently until September 2008. Delaying CD until November significantly (P < 0·05) reduced herbage mass (by approximately 500 kg DM ha^?1) and LAI (by approximately 0·86 units) in mid‐February. On average, 35% of herbage mass present on swards on 20 February was grown between 28 November and 30 January. LAI was positively correlated with herbage mass (R² = 0·78). Herbage mass increased by approximately 1000 kg DM ha^?1 as spring grazing was delayed from February to April. Tiller density increased from November to February, although it did fluctuate, and it was greatest in April (9930 m^?2). This experiment concludes that in the south of Ireland adequate herbage mass for grazing in early spring can be achieved by delaying closing to early mid‐October; swards required for grazing after mid‐March can be closed during November.     

Setting management limits for the production and utilization of herbage for out-of-season grazing

Three experiments were carried out on perennial ryegrass‐dominant swards to provide a basis for recommendations for the limits to (a) building up and timing of utilization of a herbage ‘bank’ for out‐of‐season grazing and (b) duration and intensity of early spring grazing in the United Kingdom and Ireland. In experiment 1, the effect of regrowth interval (from 7 September, 20 October, 17 November or 15 December) in autumn on herbage accumulation, leaf turnover and on subsequent spring growth was investigated. Swards regrown from early September reached maximum herbage mass (about 3 t ha^–1 DM) and leaf lamina content in mid‐November, by which time senescence rate exceeded rate of production of new leaves. New leaf production and senescence rates were greater in swards remaining uncut until December than in those cut in October or November. Time of defoliation up to December had no effect on spring herbage mass in the subsequent spring. Defoliating in March reduced herbage mass in late May by less than 20%. Experiment 2 investigated the progress in herbage growth and senescence in swards regrowing from different times in late summer and autumn to produce herbage for utilization beyond the normal grazing season. Treatments in a randomized block design with three replicates were regrowths from 19 July, 8 August, 30 August and 20 September. Based on a lower ceiling of leaf and total herbage mass being reached with progressively later regrowths, beyond which leaf senescence generally exceeded leaf production and herbage mass declined, it was concluded that currently recommended rotation lengths for this period should extend from 3 weeks in late July to 8 weeks for swards previously grazed in mid‐September. In both experiments, leaf senescence commenced earlier (by one leaf‐age category) than previously published estimates and so brought forward the time at which senescence rates balanced leaf growth rates. In experiment 3, designed to evaluate the effect of daily grazing period and intensity in early spring on herbage regrowth, dairy cows grazed successive plots (replicates) for 2 or 4 h each day at two intensities (target residual heights of 5 or 7 cm) in March to mid‐April. Regrowth rate was similar in all treatments including the ungrazed control, despite soil moisture content being relatively high on occasions. Tiller density was significantly reduced in May by grazing plots in early or mid‐April. It is concluded that in autumn there are limits to which rotation lengths should be extended to produce herbage for out‐of‐season grazing owing to attainment of ceiling yields. Although utilization in early spring may reduce herbage availability in spring, out‐of‐season utilization need not reduce herbage growth rates in early spring.     

The effects of contrasting cutting regimes on the components of clover and grass growth in microswards

Microswards of white clover and perennial ryegrass were subjected to one of four treatments: weekly cutting to 3·5 cm, weekly cutting incorporating a period of no cutting for 6 weeks starting 27 April (early rest), weekly cutting incorporating a period of no cutting for 6 weeks starting 8 June (late rest), or cutting every 3 weeks. Two sward types were used: a mixture of white clover cv. Milkanova with perennial ryegrass cv. Melle, and white clover cv. Kent with perennial ryegrass cv. Melle. Growth measurements (leaf appearance, branching/tillering and stolon internode length) were confined to the first three treatments with records collected during contiguous 21-d measurement periods. Vertical height increments of clover and grass and red:far-red light ratios at the sward bases were also recorded at frequent intervals. At the end of the experiment population densities and unit weights were recorded for all treatments. Significant treatment effects on the rate processes were largely confined to the 21-d period immediately after weekly cutting of rested swards had resumed. On previously rested compared with weekly cut swards, clover leaf appearance rates were increased by 40% and branching rates by 164%. During the same period, grass leaf appearance rates were reduced by 50% and net tillering changed from positive to negative values. Though the rate responses were transient, effects were still apparent at harvest in September, when population density and content (proportion by population density and weight) of clover were significantly higher in the late rest treatment. The variety Kent showed a consistent, though usually nonsignificant, higher leaf appearance and branching rate compared with Milkanova, and in September was characterized by a higher population (7400 m^?2 compared to 3200 m^?2) of smaller units (27 compared to 46 mg/apical meristem) than Milkanova. The results are discussed in relation to defoliation effects and the role of light quantity and quality as they influence the component growth processes. Attention is drawn to the importance of canopy structure and the climatic and/or phenological differences in the relative seasonal behaviour of clover and grass, together with varietal variation within species in influencing responses to management manipulations.     

Forage availability from a temperate pasture managed with intensive rotational grazing

Successful integration of rotational grazing into livestock production systems requires estimates of pasture growth rates for feed budgeting of daily animal intake. By matching livestock nutrient demand with forage availability, over-feeding of supplements can be minimized, which reduces feed costs and the need lo manage surplus nutrients, A three-year grazing study was carried out on a Kentucky bluegrass ( Poa pratensis L.)-dominant pasture to estimate the daily quantity of herbage available to cattle in an intensive, rotational grazing system. Herbage production, species composition, and forage quality were determined in each of the six grazing cycles in a year, from April until September. The average length of a grazing cycle was 28·6 d, with 2·7 d for duration of grazing on a paddock. Pre-grazing and post-grazing sward heights, measured with a plate meter, were 14 and 7 cm, and the corresponding herbage masses were 1955 and 775 kg DM ha⁻¹ respectively. Under adequate soil moisture during 1989, herbage available for daily intake was 53 kg ha⁻¹ from April until mid- August, declining to approximately 32 kg ha⁻¹ d⁻¹ by the end of September. Distribution of this herbage was fairly uniform until the end of August. However, a dry summer in 1991 reduced herbage availability to 15 kg ha⁻¹ d⁻¹. Bluegrass and white clover ( Trifolium repens L.) formed 70% of the herbage yield during the period April–June. Later in the season, dead matter and other species increased, reducing the contribution of bluegrass and clover to approximately 60% of total dry matter. While these pastures have the potential to provide significant amounts of forage for 5–6 months in a year, additional on-farm forage reserves are needed during periods of water stress.     

Effect of sowing date of triticale on seasonal herbage production in the central Appalachian Highlands of the United States

Triticale (X Triticosecale Wittmack) was evaluated as a complementary pasture to buffer those periods when herbage production from mixed perennial pasture is marginal in the central Appalachian Highlands of the United States. Triticale was sown every month from May to October for five consecutive years from 1999 to 2003. Plant population structure and herbage production were evaluated at intervals until May of the year following establishment. Triticale established quickly at all times of sowing except late October. Wet summers resulted in foliar disease and a rapid decline in plant density when triticale was sown in May and June. In contrast, during the relatively dry summer of 1999, triticale stands exhibited minimal decline. Triticale sown in August had a herbage yield of 1580 kg DM ha^?1 when harvested in October which was over twice the herbage yield of triticale sown in May, June and July. Average herbage yield in the following April of triticale sown in September was higher (1750 kg DM ha^?1) and less variable than herbage yields from other sowing dates. Plant and tiller populations declined throughout the following April but herbage yields in May were high due to stem and seed head development associated with reproductive growth. Incorporating areas of triticale into mixed‐species perennial pasture systems could buffer herbage production during hot and dry summer periods as well as during cool periods of late autumn and early spring.     

Growth, colonization and productivity of two white clover cultivars strip-seeded into an upland Festuca-Agrostis sward

Small plots of a Festuca-Agrostis upland sward on a peaty gley podsol were strip-seeded during late June 1986 with white clover cvs Aberystwyth S184 or Menna at 4 kg ha⁻¹ and defoliated early (20 August) or late (3 September) and then frequently or infrequently (every 2 weeks or 4 weeks) until the end of September. All plots were defoliated in early November, at 3-weekly intervals during the growing season in 1987 and then grazed rotationally during 1988.
Satisfactory seedling establishment, representing 46% emergence, was achieved 5 weeks after sowing. The differential defoliation regimes had no persistent significant effects on clover development. S184 soon produced more leaves per seedling than Menna and a smaller proportion of its leaf number and weight were removed at each defoliation. Following large losses of leaves over the 1986–87 winter, SI84 had significantly more leaves per stolon than Menna; subsequently it also colonized the sward at a quicker rate. During 1987 amounts of herbage harvested (6.1 t ha⁻¹) were similar with the two clover cultivars, with S184 contributing 47% and Menna 44% of this respectively. SI84 made a larger contribution to yield during May and June but Menna was more productive during September and October. During 1988 clover populations were maintained with rotational grazing without additional fertilizer inputs.
The results show that, despite initial soil and climatic contraints, both small and medium-leaved clovers can be strip-seeded into upland swards with large subsequent benefits to yield and herbage quality. However, they also indicate the need for further experiments to determine the influence of sward morphology and defoliation regime on stolon branching rates and accumulation of growing points which, in turn, govern sward colonization.     

The effect of time of harvest on seed production of three red clover cultivars

Small plots of red clover cv. Sabtoron, S123 (diploids) and Hungaropoly (tetraploid) were harvested for seed production at two-week intervals from 19 August to 17 October inclusive in 1981, inflorescence appearance rate, bee density and components of yield having been monitored throughout the summer. Inflorescence appearance rate reached a maximum at the end of July/early August for Hungaropoly and Sabtoron and during mid-August for S123. Bee density followed a similar pattern. Florets and seeds per inflorescence and 1000-seed weight decreased as flowering progressed except during the first three weeks in July. Potential seed yield was calculated from the components of yield for the harvests taken on 3 and 18 September. Losses in seed yield (difference between actual and potential) up to and during harvesting, threshing and cleaning were lower in the tetraploid cultivar (27–39%) than the diploid cultivars (35–l55%). Each cultivar had an optimum harvest time before which yield was affected by immature seeds and beyond which it was adversely affected by shedding of inflorescences and seeds and sprouting of seeds on the inflorescences. The optimum time to harvest Sabtoron was early September, Hungaropoly early to mid-September and the late flowering cultivar S123 mid-September when less than 4% of the inflorescences were still unripe. Seed yield and inflorescences per unit area were lower in the tetraploid cv, Hungaropoly (maximum 542 kg ha⁻¹) than diploid cv. Sabtoron and S123 (864 and 897 kg ha⁻¹ respectively) although the tetraptoid had heavier seeds. It is concluded that the optimum time to harvest red clover for seed production is about three or four weeks after the end of the period of rapid inflorescence production and that this coincides with the time when only a small proportion of unripe inflorescences remain.     

Area control of the green peach aphid on peach and the reduction of potato leaf roll virus

Peach trees in a 500-mile² (1295 sq. K) area were sprayed during April and May each year from 1966 to 1969 to control the wingless fundatrix form ofMyzus persicae (Sulzer) after the overwintering eggs had hatched and before subsequent generations of the aphids had developed wings and migrated to summer host plants. The results were monitored from 1966 to 1971 by using about 60 yellow water trap pans each year to collect winged aphids in the control area. Also, aphids were counted weekly in about 30 potato fields each year. Samples of potato tubers collected from the 30 fields (and from 34 other fields in 1965) were indexed for net necrosis and then planted and indexed for chronic leaf roll. The early spraying reduced the populations of winged aphids collected in traps in May and early June 1966–1969 by about 60% compared with the post-spray years (1970–1971). The amount of net necrosis found in potato tubers from the control area was reduced from 11 % in 1965 to slightly more than 3% from 1967 through 1969 and the chronic leaf roll in plants was reduced from 43% in 1965 to about 10% for the same years. Only after two years of spraying was there evidence of a significant reduction in the spread of the virus; similarly, not until 2 years (1970 and 1971) following the end of the spray program did the virus increase significantly.     

The influence of autxunn cutting regime on the response to temperature of leof growth in perennial ryegrass

Plots of perennial ryegrass were cut in September, October, November and December 1975, and soil surface temperature, leof extension rates, appearance rates and lengths were measured between September 1975 and April 1976. Cutting on progressively later dates in the autumn reduced leof extension rates and leof lengths throughout the following winter and spring, whereas leof appearance rates were reduced for only about 1 month ofter cutting.     

Sward growth under cutting and continuous stocking managements: sward canopy structure, tiller density and leaf turnover

The change in structure of continuously grazed versus infrequently cut swards of perennial ryegrass ( Lolium perenne L), cv. S23, was investigated during their first full harvest year. Measurements were made from early May until late September. The intensity of stocking by sheep in the grazed sward was adjusted in an attempt to maintain a high level of radiation interception and the cut sward was harvested at approximately monthly intervals.
The herbage mass, lamina area index and radiation interception of the cut sward varied in a cyclic pattern between harvests but in the grazed sward these parameters showed considerably less variation, although they all increased early in the season and then declined later. The proportion of dead material above ground increased throughout the season in both sward types but was more marked in the grazed sward.
There were major differences between the grazed and cut swards in the number of tillers per unit ground area; the difference became more marked throughout the season and by September the tiller densities in the grazed and cut swards were 3·20⁴ m^-2 and 6·20³ m^-2 respectively. Divergence in tiller density was associated with differences in specific stem weight and leaf area per tiller.
Rates of appearance and death of leaves on tillers in the grazed sward were determined. During May, leaf appearance exceeded leaf death but this was reversed in June. During the rest of the season as a new leaf appeared on a tiller so the oldest leaf died.     

Establishment and production of common sainfoin (Onobrychis viciifolia Scop.) in the UK. 1. Effects of sowing date and autumn management on establishment and yield

The effects of sowing date and autumn management of sainfoin ( Onobrychis viciifolia Scop.) were investigated over 3 years in the UK. Replicated plots were sown between April and September in 2003 and 2004. Autumn management treatments were early and late cutting carried out in the establishment year and in subsequent years. Dry matter (DM) yields were measured over 3 years. One harvest was taken from April to July sowings in the establishment year and three harvests in each of the following years. DM yields from sowings in April and May were 2·8 and 3·3 t DM ha⁻¹, respectively, in the establishment year, which were higher ( P  <   0·001) than from sowings in June and July. Sowings from April to July yielded 10·9–12·5 t DM ha⁻¹ in the first full-harvest year, and 9·5–11·5 t DM ha⁻¹ in the following year. Sowings in August and September only gave 5 t DM ha⁻¹ year⁻¹. Early-autumn cutting of an established sward reduced yields of sainfoin at the second harvest in the first and second full-harvest years. Sowing in May had the lowest proportion of weed species (0·06) in the establishment year, and sowing in July had the highest (0·53). Crude protein concentration increased as the seasons progressed from 149·8 to 230·1 g kg⁻¹ DM.     

Effects of an autumn defoliation on overwintering, spring growth and yield of a white clover/grass sward

An established sward of binary mixtures of meadow fescue (Festuca pratensis) and white clover (Trifolium repens) (either AberHerald, Grasslands Huia or Sandra) was subjected to (A) no further defoliation, (B) a defoliation in late September or (C) a defoliation in late October after four harvests had been taken during the grazing season. About a tonne of dry matter (DM) was removed by the autumn defoliations. There were two levels of nitrogen application in spring, either 0 or 90 kg ha^?1. The development of grass and clover morphology and population sizes from early autumn until the first harvest the following year was followed by regular sampling of the above-ground material. Stolons were analysed for total non-structural carbohydrates (TNCs), and the temperature at stolon level was continuously recorded. There were no interactions between autumn defoliation, clover cultivar or nitrogen treatments on any of the parameters studied. White clover growing-point numbers and stolon morphological characteristics were reduced in size during the winter and did not recover during the spring. A defoliation in late September resulted in the greatest reduction, whereas there were no differences between the other two treatments. The grass tiller population increased from early autumn until the last sampling occasion in May, but both autumn defoliations resulted in a smaller increase. Defoliation in late September had the greatest impact. The TNC content of white clover stolons fell from about 350 g kg^?1 to 150 g kg^?1 DM from late autumn until late April. There were small differences between the treatments, but a defoliation in late September resulted in a significantly lower level in late autumn. The temperature amplitude at stolon level was consistently greater in plots defoliated in late September. Total DM harvested in spring was 4367, 2564 and 3536 kg ha^?1, of which 388, 352 and 460 kg ha^?1 was white clover, from treatments A, B and C respectively. It is concluded that an autumn defoliation may affect the overwintering of white clover negatively, but that the effect on the grass may be even more detrimental.     

Year-Round Cultivation of Sweet Sorghum [Sorghum bicolor (L.) Moench] through a Combination of Seed and Ratoon Cropping in Indonesian Savanna

We studied the year-round cultivation of sweet sorghum, which is a raw material for the fermentation of monosodium glutamate, in East Java, Indonesia. In this savanna area, each year comprises 2 seasons–dry (April–September) and rainy (October–March). Seed crops were sown almost every month for 1 yr, and each seed cropping was followed by a ratoon cropping after the seed crop harvest. The stem-related traits of plants from different sowing or ratooning dates were studied at around 17 weeks after sowing or ratooning. For both plants derived from seed and ratoon, better crop establishment was observed when cultivation was commenced during the rainy season than during the dry season. Although sowing was undertaken each week in August and September during the most severe dry period, germination rate was very low (or zero) and even the germinated plants died within a short time. In contrast, ratoon cropping was started and plants were grown until harvest. In East Java, it is considered possible to produce sweet sorghum throughout the year, mainly by sowing, but also partially by ratooning during the most severe drought period of the dry season.     

Annual cool-season legumes for forage production in mild winter areas

The forage potential of several annual winter legumes – crimson clover ( Trifolium incarnatum L.), faba beans ( Vicia faba L.), forage peas ( Pisum sativum L.), serradella ( Ornithopus sativus Brot.) and vetches ( Vicia sativa L. and Vicia villosa Roth.) – was evaluated over two growing seasons in the wet and mild winter areas of Galicia (north-west Spain) with a moderately acid soil, at the two normal harvesting dates in the region, April and May.
The results indicate that, in April, serradella and crimson clover (in the warmer location), can produce dry-matter (DM) yields of 4–5 t ha⁻¹, which is similar to other winter forages in the same area, with an average growing season of 212–237 d, corresponding to about 339–420 accumulated degree–days above 10°C (GDD₁₀). In May, mainly in the warmer location, fava beans, peas and vetches yielded on average 4·7–8·5 t ha⁻¹ DM, with an average growing season of 166–206 d but with only 233–278 GDD₁₀ units. Faba bean, with an average of 8·5 t ha⁻¹ DM in the May harvest, was the highest producing forage legume. The results also suggest that some cool-season legumes could fit into double-cropping systems based on summer crops, such as maize, because of their forage yields and nutritive value. However, in order to produce consistent DM yields, the date of sowing is crucial; they must either be sown much earlier than the dates in this study or the harvests must be delayed until the end of April.     

The productivity of May-lambing ewes grazed at three stocking rates on lowland grass

For the 2 years 1977 and 1978 Masham ewes grazed a perennial ryegrass ( Lolium perenne cv. S24) pasture from the beginning of April until the end of September each year. Twelve ewes were allocated to each of the three stocking rate treatments, 12 (L), 16 (M) and 20 (H) ewes per ha. Each treatment was rotationally grazed around six paddocks with a forward creep for the lambs. Conservation cuts were taken from each treatment in late May and were generally sufficient to cover a 3-month winter feeding period for treatments L and M but were always insufficient for treatment H. Lambing took place at pasture during the second half of May. No concentrates were fed to the ewes during late pregnancy or lactation but lamb birth weights (4–8 kg) and lamb growth rates over the first 4 weeks (240 g d^−l) were satisfactory. Organic matter intakes (OMI)of grass by the pregnant ewes(1816,1844 g OMI ewe⁻¹) were not affected by the stocking rate. Intake of grass by the lactating ewes was affected by year and by stocking rate. The overall growth rate of lambs was higher on treatment L than either M or H but decreased on all treatments during the latter half of the grazing season, resulting in 43% of L and only 3% of M and H lambs being fit for slaughter by the end of September. The main features of this time of lambing are low costs and the production of predominantly store lambs.     

Implications of nitrogen fertilizer applications and extended grazing for the N economy of grassland

The response of swards which have been previously grazed to N fertilizer applied in early February was studied in two experiments in Northern Ireland. The effect of N fertilizer applied at a range of dates in autumn and spring on swards for out-of-season utilization was studied in a further experiment. Deep soil coring was also undertaken, subsequent to grazing with dairy cows, in grazed and protected areas in November and March to investigate the effect of out-of-season grazing on soil mineral N levels.
Dry-matter (DM) yield response to early spring N application in previously grazed swards was low, with no effect on DM yield in February or March. Progressively delaying N application (and commencement of herbage accumulation) in autumn from 8 September until 18 October reduced herbage availability in late autumn and early spring but increased leaf lamina content. The greater the amount of herbage accumulated to 1 December, the lower the tiller density in the following April.
N fertilizer had a greater impact on soil mineral N in spring than in late autumn/early winter, suggesting that fertilizer N was more prone to loss in the latter. Soil mineral N was not significantly affected by out-of-season grazing.
It is concluded that in well-fertilized, previously grazed swards response to N for out-of-season herbage is low and the probability for N loss is increased. Herbage quality will decline and the sward may be damaged if about 2 t DM ha⁻¹ or more of harvestable herbage accumulates for use in winter or in early spring.     

The effects of spring closing date on the yield and quality of perennial ryegrass and cocksfoot cut for conservation

This second paper concerned with effects of prolonged spring defoliations on two early perennial ryegrass varieties (Cropper and RvP Hay Pasture), an intermediate perennial ryegrass (Talbot) and an early cocksfoot (Roskilde) examines the effects of different closing dates on ear emergence, weekly DOMD ( in vitro ) and conservation yields. The grasses were mown fortnightly to simulate sheep grazing from January until three closing dates, 19 April, 3 May or 17 May, in 1978 and 1979. A set of plots was left undefoliated. All plots were sampled weekly from 2 or 3 weeks after 17 May until the end of June or early July.
Prolonged mowing resulted in a small delaying effect on 50% ear emergence of the ryegrasses. The maximum delay was 3 d with the latest closing date. Under this treatment, ear emergence of the cocksfoot was delayed by an average of 12 d but by only 0–4 d under the earlier closing dates. Delay in date of closing caused a significant delay in the time to reach a given DOMD but the effect was largely confined to the latest closing date and was greatest for the cocksfoot. The time when 670 g kg⁻¹ DOMD was reached was delayed in the ryegrasses by no more than 5 d, except for a 12-d delay in the intermediate ryegrass in 1978 following the late closing date. Under this treatment the delay for the cocksfoot was 8 d in both years. The early ryegrasses produced stemmy regrowths.     

云南河口香蕉黑星病的发生危害规律研究

采用定点监测、分级调查法对云南河口地区香蕉黑星病的发生规律进行研究。结果表明：降雨量及温度的异常变化对香蕉黑星病的发生危害影响最大。河口县香蕉黑星病从4月底5月初开始发病，7月份开始迅速扩散，9～10月份达到高峰值，发病率为80%～100%，且高发病率维持至12月份；不同栽培地区香蕉黑星病的危害率及病情指数差异较大，危害率依次为河口东部地区＝65.5%＞中南部地区＝51.44%＞西部地区＝48.78%，不同海拔高度的危害率及病情指数呈现出海拔越高危害性越大的趋势。     

中国橡胶树棒孢霉落叶病疫情调查及其发生规律初探

2011~2013年,项目组对云南、海南、广东和广西等橡胶主产区的棒孢霉落叶病（CLFD）疫情进行调查并对其发生规律进行了初步分析。结果发现：总共调查的81个监测点中,约有92％的监测点发现了该病的为害,且疫情逐年加重,以海南省的大丰农场、西庆苗圃、十月田苗圃和保显农场,云南省的勐醒农场、蚂蝗堡农场和坝撒农场以及广东省的红十月农场等监测点的发病率最高,病情严重。主栽品种田间调查发现,文昌11、云研277-5、云研77-4和热研7-33-97等品种的抗/耐性水平较高,而RRIM600、PR107、GT1和红星1等品种的抗/耐病性水平较差。全年病害消长动态调查发现,该病一般3~4月出现病情,8~9月病情急剧上升,10~11月达到全年最高峰,后逐步下降。多年的调查结果发现,棒孢霉落叶病的发病率和病情指数呈逐年加重趋势,且主栽品种中很少有品种（品系）表现出耐病或抗病性。     

Effect of cutting date and frequency on yield and quality of kudzu in the southern United States

Kudzu [Pueraria lobata (Willd.) Ohwi.], a vigorous, perennial warm‐season legume, grows widely throughout the south‐eastern United States, predominantly as a volunteer species. It is tolerant of drought and acidic, infertile soils and may have potential as a low‐input forage for livestock. A field experiment was undertaken to determine the effects of cutting date and frequency on yield and nutritive value of kudzu (20‐year‐old stand with no fertilizer or lime inputs) in central Georgia. The cutting treatments included an uncut control, and plots cut once (September), twice (July and September), and three times (June, July, and September) during the 1994 growing season. Dry matter (DM) production and forage quality were determined for total herbage, leaf and stem tissues from quadrat samples taken on all plots in June, July, September, and November (after a killing frost) in 1994, and in June, 1995. Total herbage and leaf DM production was highest for the three‐harvest system and lowest in the no‐cut control plots in 1994, but these results were reversed in the harvest made in 1995. Total herbage production and crude protein concentrations were similar in kudzu cut in the initial summer harvest (either June, July, or September) during the first year. Whole plant and stem in vitro dry matter digestibility (IVDMD) in these samples declined throughout the growing season, while leaf IVDMD was unchanged until the first frost. Kudzu has the potential to be a low‐input forage for livestock, particularly as supplemental drought feed, or as a protein bank for summer or autumn grazing.