Timing Of Mowing Research Articles

Fine‐tuning of a mowing regime, a method for the management of the invasive plant, Ambrosia artemisiifolia, at different population densities

Common ragweed (Ambrosia artemisiifolia) is an invasive annual plant with highly allergenic pollen. Its spread in introduced and native ranges often occurs on roadsides, where it builds stable and rapidly growing populations. The most sustainable way of controlling the population size of this species is to prevent seed production in order to deplete the soil seed bank. Populations on roadsides are submitted to regular mowing management, which can even exacerbate the situation by inducing resprouting after cutting or by accidentally spreading seeds along the road. The population density in the juvenile stages of development could play an important role in the success of cutting regimes, as it might influence the resprouting capacity of this plant. The influence of the juvenile population density and of seven cutting regimes, differing in the timing and frequency of cuts, on easily measurable reproductive traits was investigated in a glasshouse experiment. The cutting regimes had a strong influence on the reproductive success and on the phenology of the development stages of ragweed. The population density in the juvenile stages did not play a role in further phenological development, but did influence the reproductive traits. The reproduction of ragweed can be lowered by locally adapted combinations of the timing and frequency of mowing. As the optimal management option for the reduction of both the male and female flowers, the authors suggest a first cut just before the start of male flowering, followed by subsequent cuts every 3–4 weeks.

Mowing regime has different effects on reed stands in relation to habitat

Reed (Phragmites australis) is widespread in aquatic habitats in Europe where it plays an important ecological role, especially as stabilizer of lake and river shores and as filter against pollutants. Reed is also abundant in ecotones towards terrestrial habitats, especially fen meadows, where its expansion can out-compete rare slowly-growing fen species. Therefore, defining appropriate guidelines for managing reed in wetlands has to consider differences in the ecological roles that reed plays in different wetland habitats. In a small pre-alpine lake in N Italy, we mowed reed stands in three plant communities located along a transect from the lake shore to the periphery. In each community, three areas were subjected to reed mowing in late winter, as traditionally done in the past. Three additional areas were subjected to mowing in winter and summer, while three areas served as un-treated controls. Summer mowing was carried out in August, when the nesting period of birds was concluded. Mowing in winter did not affect reed aboveground biomass (RAB) in any community but enhanced the efficiency of removing nutrients by reducing litter accumulation in the soil. Mowing in winter and summer only slightly decreased RAB in the riparian community, not at all in the intermediate community but significantly diminished RAB in fen meadows. Phosphorus deficiency and/or reduced competition with other species probably accounted for RAB reduction in fen meadows. In conclusion, winter mowing can be overall recommended for preventing eutrophication of littoral habitats while summer mowing is advisable for preventing reed expansion in fen meadows. However, the timing of summer mowing has to be defined considering all requirements needed for optimal management of each individual site.

Mowing Before or After an Herbicide Application Does Not Influence Ground Ivy (Glechoma hederacea ) Control

Many turfgrass extension bulletins and herbicide labels recommend prolonging or suspending mowing practices 1 day or more before and/or after herbicide applications to increase efficacy. However, the effect of mowing timing on herbicide efficacy has not been sufficiently explored. Field experiments were conducted to evaluate the influence of herbicide selection and mowing timing relative to herbicide application on the control of ground ivy (Glechoma hederacea L.). The three mowing treatments included mowing 30 min before herbicide application, mowing 30 min after herbicide application, and not mowing for at least 7 days prior to and at least 3 days after herbicide application. Aminocyclopyrachlor resulted in the greatest reduction of ground ivy cover in 2011 and 2012. Like aminocyclopyrachlor, 2,4-D ester and metsulfuron reduced ground ivy cover both years, while triclopyr reduced ground ivy cover as well as aminocyclopyrachlor in 2012. Although 2,4-D + mecoprop (MCPP) + dicamba was not among the best performing herbicides, it reduced ground ivy cover compared with the untreated check in both years. There were no mowing or mowing-by-herbicide interactions on any of the rating dates. Thus, this research suggests that the timing of lawn mowing relative to herbicide application has little measurable impact on herbicide efficacy on ground ivy.

Intake and digestibility by sheep, in situ disappearance in cannulated cows, and chemical composition of crabgrass hayed at two moisture concentrations and treated with a non-viable Lactobacillus–lactic acid additive

Crabgrass (Digitaria ciliaris [Retz.] Koel.) is a high-quality warm-season annual that can be used as hay, but field curing time may be lengthy compared with other forages. A 1.6-ha field of common crabgrass was divided into 12 plots (8.25m×50m) that were used in a randomized complete block design with a 2×2 factorial treatment arrangement to determine the effects of a non-viable Lactobacillus–lactic acid additive and moisture concentration at baling on heating characteristics and pre- and post-storage chemical composition. Half of the plots within each block were treated with 0.081ml/mg dry matter (DM) of a solution containing 110g lactic acid/kg and non-viable Lactobacillus acidophilus at the time of mowing (T) and half were not treated (U). Within T and U plots, half were baled in small square bales at 163g moisture/kg DM (L) and half at 251g moisture/kg DM (H) of moisture. Six bales per plot were selected at random, weighed, and stored in separate insulated 6-bale stacks. Core samples were taken from 3 bales initially and 3 bales post-storage. Initial bale moisture concentrations were greater (P<0.05) and initial neutral-detergent fiber (NDF) concentrations were lower (P<0.05) from H vs. L. Post-storage concentrations of NDF and acid-detergent insoluble N (ADIN; g/kg DM and g/kg N), were greater (P<0.05) from H vs. L. Dry matter intake in sheep was unaffected (P>0.05) by either treatment, but DM digestibility and digestible DM intake were both positively affected (P<0.05) by the spray treatment. In addition, DM digestibility was also affected (P<0.05) by moisture, with H>L. In situ DM disappearance was largely affected by spray treatment×moisture interactions (P<0.05). The immediate soluble fraction and effective ruminal disappearance were greater (P<0.05), and the undegraded portion in the rumen was less (P<0.05) for HT compared to HU, indicating a positive relationship between applied spray treatment and digestibility of high-moisture crabgrass. Treating crabgrass with the additive at mowing may not affect forage chemical composition, but may improve digestibility in hay baled at elevated moisture levels.

Response of sowed, flowering herbaceous communities suitable for anthropic Mediterranean areas under different mowing regimes

Growing traditional ornamental plants in urban soil often fails, due to the low quality of the soil modified by anthropic activities. The aim of this research was to study the behavior of herbaceous plants suitable for sowing in mixes in order to revegetate soils in different urban environments.Three different mixes of herbaceous plants were studied: N (native) was composed of autochthonous species, US (urban short) and UT (urban tall) were composed of both autochthonous and allochthonous species. Plant height was lower than 60cm in N and US, and above 60cm in UT. Each mix was sown in three randomized plots and each plot was mown at three different times: 110, 140 and 170 days after sowing (early, mid and late season respectively). Number of plants per square meter, plant height and biomass were recorded at each mowing time. In order to assess how well the plants would establish themselves we calculated the Shannon diversity index, the evenness of species and Simpson's index of dominance.The N mix composed of autochthonous species resulted to be well-balanced with an equal number of annual and perennial species grown. The presence of annuals and perennials made the community richer and the individual plants more evenly distributed. The best mowing time to improve diversity in all the mixes was late-season. Our study suggests that native species from southern Europe are suitable for creating diverse herbaceous communities for ornamental purposes, thus enhancing the role of Mediterranean urban areas in the conservation of biodiversity.

Chemical composition, intake by sheep, and in situ disappearance in cannulated cows of bermudagrass hayed at two moisture concentrations and treated with a non-viable Lactobacillus-lactic acid preservative

Bermudagrass [ Cynodon dactylon (L.) Pers.] is commonly used for grazing and haying in the southern USA, but hay curing can be challenging due to frequent rainfall events during spring and early summer. An existing stand of ‘Greenfield’ bermudagrass was divided into 12 plots using a randomized complete block design with a 2×2 factorial treatment arrangement to evaluate the influence of a non-viable Lactobacillus-lactic acid preservative and moisture concentration at baling on chemical composition, intake by sheep, and in situ disappearance in cattle. At time of mowing, half of the plots in each block were either spray-treated (T) or not treated (U) with 81 mL/t forage dry matter (DM) of the preservative solution. Hay was then baled at target moisture concentrations of either 174 g/kg DM (L) or 267 g/kg DM (H). Maximum temperature and heating degree days were greater (P<0.05) from H compared with L during the 42-d storage period. An interaction between spray and moisture treatments tended (P<0.10) to affect recovery of DM; recoveries for LT (0.992) differed (P<0.10) from HT (0.913), but LU and HU were intermediate between the spray-treated hays, and did not differ from either (P>0.10). Post-storage nutritive value was largely influenced by moisture treatments only. Intake and digestibility, and in situ DM disappearance of these same hays were determined using 16 wether lambs (43 ± 3.7 kg initial BW), or six ruminally cannulated cows (617 ± 3.5 kg initial BW), respectively. Dry matter intake by sheep was not affected by either treatment factor (P>0.05), but DM digestibility and digestible DM intake were greater (P<0.05) from U compared with T. The in situ immediately soluble DM portion was greater from (P<0.05) L compared with H, but the reverse was true for the potentially degradable DM fraction. The lag time tended (P<0.10) to be greater from H compared with L. Treating bermudagrass with a non-viable Lactobacillus acidophilus-lactic acid spray product at time of baling may not offset the negative effects on forage quality and digestibility of baling bermudagrass hay at excessive moisture concentrations.

Reproductive timing and investment in relation to spring warming and advancing agricultural schedules

Advances in mowing schedules have led to early and rapid declines in the seasonal food availability for, and survival rates of, chicks of grassland-breeding waders. Concurrently, increased levels of soil fertilization may have improved food abundance for adults. These developments are assumed to have resulted in an advancement of laying during 1930–1976 in several meadowbird species, including Black-tailed Godwits. Despite an apparent selective advantage of early breeding, after 1976 Godwits stopped advancing their laying dates. We have analyzed the timing of breeding and reproductive investment in Dutch Black-tailed Godwits relative to recent changes in agricultural practices and climate during 1976–2007. Early and late spring temperatures and precipitation in March were used as indicators for the timing of fertilizer application and mowing, and also as qualitative measures of relative food availability for adults and chicks. When precipitation was higher in March, Black-tailed Godwits laid earlier. Following warmer winters, the earliest females laid larger eggs, which hatched heavier chicks with a higher survival probability. We suggest that the positive effect of an increasing March precipitation on invertebrate abundance may be constrained by the current policy of rigid control of the water table. This policy prevents Godwits from further advancing laying dates, which would increase their chick’s survival prospects under increasingly early mowing schedules. Policy-makers should, next to delaying mowing schedules, also consider reduced draining in early spring as a tool to help stop the population decline of the Black-tailed Godwit.

Long‐term effects of agri‐environment schemes on breeding passerine populations in a lowland hay‐meadow system

Capsule Mowing postponement in 25% of a meadow system may lead to improved but instable population dynamics in meadow birds. Aim To monitor the long‐term effects of mowing postponement on the abundance and territory density of meadow passerines in 25% of a 3000‐ha hay‐meadow area in the Saône Valley (eastern France). Methods From 1993 to 2009, passerine abundance was measured annually in 78 plots using point counts and territory density was assessed in two study areas by Territory Mapping. Results The programme of mowing postponement led to substantially increased passerine abundance and territory density, with the highest increase detected in Whinchats Saxicola rubetra. No positive trend was observed in Corn Buntings Emberiza calandra. Immediately after the increase in abundance, bird distribution within the study area was not influenced by the timing of mowing. The hatching success, assessed by the systematic observation of food carrying, was negatively influenced by early mowing (<40% recorded when >60% of the meadow area was already harvested on 1 July) or, in late mown areas, by high meadow passerine territory density (<40% when territory density was >10 per 10 ha). Hatching rate was usually higher in Whinchats than in Corn Buntings. Conclusion By improving meadow passerine breeding outputs and density, mowing postponement led to instable population dynamics with dominance of certain species and density‐dependent breeding success.

Effects of mowing date on the opportunities of seed dispersal of ditch bank plant species under different management regimes

Mowing and plant removal is a traditional practice in low-intensity farming and likely to lead to high plant species richness. Even today, scientific knowledge on the impact of mowing on seed availability is still very limited. We studied whether the seed availability of ditch bank plant species was affected by the timing of mowing and, if so, whether the effect varied according to management regime (nature reserve, agri-environment scheme (AES) with long-term management, AES with short-term management, conventional management). Our focus was on seed availability for transportation, because restoration of ditch bank vegetation is known to be limited by seed dispersal. The presence and seed-setting of 25 target species in 384 plots were recorded at the mowing date, under four management regimes. A Hierarchical Generalised Linear Model (HGLM) was used to analyse the effects of mowing date and management on the number of species setting seed. It suggests that when the mowing is twice annually, mowing on July 1st and on September 1st will result in a maximum number of species of which the seeds are available for transportation and, therefore, create largest opportunities for seed dispersal on ditch banks in the western peat area of the Netherlands. The effect of mowing date differs among species, with certain rare species like Caltha palustris and Lythrum salicaria in particular differing from the commoner species. A flexible mowing regime varying from year to year would therefore help to protect these rare species. The later peak in seed-setting found in nature reserves and long-term AES suggest a postponed mowing compared to conventionally management and short-term AES.

Simulated Rainfall and Mowing Impact Fungicide Performance When Targeting Dollar Spot in Creeping Bentgrass.

In this 2-year field study, four chemically diverse fungicides (i.e., chlorothalonil, boscalid, iprodione, and propiconazole) were evaluated for their ability to control dollar spot (Sclerotinia homoeocarpa) in creeping bentgrass (Agrostis stolonifera) as affected by simulated rain and mowing timing. Simulated rain (25 to 32 mm) was imposed about 30 min after fungicide application and was compared to rain-free plots. One set of plots was mowed in the morning when the canopy was wet with dew and compared to plots that were mowed when the canopy was dry in the afternoon. The percent reduction in dollar spot control associated with simulated-rain versus rain-free treatments in 2007 and 2008, respectively, was as follows: chlorothalonil 67 and 83%; propiconazole 42 and 79%; boscalid 48 and 70%; and iprodione 33 and 66%. When disease pressure was low, all fungicides subjected to simulated rain provided effective dollar spot control for 7 or more days following the initial application in each year. Across all fungicide-treated plots over 2 years, the average percent reduction in dollar spot associated with morning mowing ranged from 54 to 65%. The reduction in dollar spot severity in morning-mowed plots improved the performance of all fungicides.

Short-term successional change does not predict long-term conservation value of managed arable field margins

Field margins have been widely advocated as a means of integrating agronomic and biodiversity objectives and are included in agri-environment schemes across Europe. However, information on the long-term development of field margin plant communities remains limited. We describe a long-term experiment on the effects of field margin management on biodiversity and weed species. Swards were established by natural regeneration or sowing a grass and wildflower seed mixture, and treatments manipulated the frequency and timing of mowing, application of herbicide and leaving of hay. Vegetation was monitored to evaluate the extent to which early conclusions remained valid after 13 years. Although early successional trends suggested that naturally regenerated swards would rapidly become dominated by pernicious perennial weeds, and that sown swards would exclude such species, neither was true in the longer term. Sown swards were eventually invaded by unsown perennials, but they remained distinct from naturally regenerated swards. Plant species richness declined throughout the experiment. Annuals were lost most rapidly from sown swards but, under natural regeneration, loss could be modified by mowing. Perennial species initially increased during natural regeneration before stabilising. In sown swards they declined under all treatments. Species richness in naturally regenerating swards was promoted initially by mowing twice annually. After 13 years, timing and frequency of mowing had no significant effect on species richness although it still influenced sward composition. Leaving cut hay lying produced species-poor swards. We conclude that the choice of establishment and management methods for arable field margins significantly affects the long-term conservation value of the swards.

Biodiversity and Traditional Land Use in South-Central Sweden: The Significance of Management Timing

Abstract During the last 50-100 years, large numbers of species associated with semi-natural grassland have declined. One reason for this is the considerable reduction of grassland area. Another possible explanation is the loss of historical management practices. This study addresses changes in the timing of management and its implications for biodiversity, and combines historical data on management timing (eighteenth century) with data on reproductive phenology of vascular plants and butterflies. All data are from south-east and south-central Sweden and demonstrate a considerable loss of grassland area, but an even greater loss of historical management practices. Historically, 21-32 per cent of the semi-natural grassland area was subject to late season management (from early July onwards) by mowing or late-season grazing. In 2005, management had ceased in 97-99 per cent of the historically managed grassland, and current management was dominated by all-season grazing. 0.2 per cent of the grassland area was managed by mowing in 2005. Historically, at the time of mowing, 50-80 per cent of the butterfly species and 20-95 per cent of vascular plant species had completed their reproductive cycles, the proportions increasing with the later onset of management. The results suggest that the reduced use of late management is a major cause of the observed decline of grassland organisms.

Mechanisms of structural change derived from patterns of seedling emergence and mortality in a semi‐natural meadow

AbstractQuestions: Is seedling emergence limited by the set of viable seeds, by incompatibility between the phenology of seed shedding and timing of mowing, or by dry weather in germination periods?Does seedling mortality fluctuate with season and weather?Location: Negrentino, southern Alps, Switzerland.Methods: Fecundity estimates of the dominant grass Bromus erectus; highly frequent counts of spontaneous seedlings by species and calculation of a community‐level average mortality rate across 5 years; species‐level records of seed shedding date and measurements of seed mass; measurement of soil moisture.Results: B. erectus produced 143.9 viable seeds/m2/year while the density of its seedlings was a 55 times smaller fraction. Grasses had fewer seedlings than forbs and their phenology of seed shedding was less compatible with mowing date. Soil moisture was a strong determinant of seedling emergence in spring and less so in autumn. Average seedling mortality declined with age of the populations and reached a maximum in an extremely dry summer. In relatively wet summers establishment success was positively related to seed mass.Conclusion: Community structure is susceptible to drought through mechanisms that selectively reduce recruits of coexisting plant functional groups. We propose that (1) more frequent intense droughts tend to reduce species that depend on frequent recruitment from seed, hence favour long‐lived clonally spreading species, (2) drought timing selects between species with different germination phenology and drought resistance, and (3) drought impacts can be mitigated by changing management regimes that affect seed shedding.

Effect of different mowing regimes on butterflies and diurnal moths on road verges

In northern and central Europe road verges offer alternative habitats for declining plant and invertebrate species of semi-natural grasslands. The quality of road verges as habitats depends on several factors, of which the mowing regime is one of the easiest to modify. In this study we compared the Lepidoptera communities on road verges that underwent three different mowing regimes regarding the timing and intensity of mowing; mowing in mid-summer, mowing in late summer, and partial mowing (a narrow strip next to the road). A total of 12,174 individuals and 107 species of Lepidoptera were recorded. The mid-summer mown verges had lower species richness and abundance of butterflies and lower species richness and diversity of diurnal moths compared to the late summer and partially mown verges. By delaying the annual mowing until late summer or promoting mosaic-like mowing regimes, such as partial mowing, the quality of road verges as habitats for butterflies and diurnal moths can be improved.

How can we protect rare hemiparasitic plants? Early-flowering taxa ofEuphrasia andRhinanthus on the Baltic island of Gotland

Euphrasia stricta var.suecica, E. stricta var.tenuis, andRhinanthus serotinus subsp.vernalis are three endangered, hemiparasitic annual herbs found in traditionally managed hay meadows on Gotland, Sweden. We have studied — experimentally and in the field — how some features in the present and traditional management cycle affect their fitness. We set up permanent 50 × 50-cm plots in a coastal hay meadow where bothE. stricta var.suecica andRhinanthus are still quite common. The survival, growth and fecundity of cohorts ofEuphrasia andRhinanthus were followed throughout the growing season for three years. The length of the growing season was vital forEuphrasia andRhinanthus performance. In cooler summers, the percentage ofEuphrasia individuals that produced mature seeds was decreased by 20% at the time of mowing. This indicates the need to individually adjust the time of mowing, as was formerly done, to the actual phenological development in order to maintain healthy populations. It is also important to consider the effect of time of mowing on total species richness, asEuphrasia more successfully established in 10 × 10-cm squares with high species richness. Also, the time in spring when hemiparasite growth started was crucial. Cohorts of bothEuphrasia stricta var.suecica andRhinanthus that connected to hosts and started growing early in the season had a strong advantage over later cohorts by having fitness values four to eight times higher. From this we conclude that the traditional practice of spring raking is important for the long-term persistence of these hemiparasites, since raking promotes an earlier onset of both host and hemiparasite growth. Another important issue is the traditional, but nowadays often neglected practice of letting the hay dry in the meadow after mowing. Hay that was left to dry in the meadow contributed significantly moreRhinanthus seed to the meadow than hay that was taken away immediately after mowing. We also found that seedling emergence and subsequent growth ofEuphrasia stricta var.suecica was greatly enhanced by a second hay cut in September. A second cutting mimics some of the positive effects of the traditional practice of aftermath grazing, which is nowadays often abandoned.

Long‐term compositional responses of a South African mesic grassland to burning and mowing

AbstractQuestion: What is the long‐term compositional response of grass and forb species to various combinations of burning and mowing? Can these responses be predicted from simple plant traits?Location: Ukulinga research and training farm (24°24′E, 30°24′S), Pietermaritzburg, KwaZulu‐Natal, South Africa.Methods: Grass species relative abundance in 1996 in various burning and mowing treatments of a long‐term (&gt; 50 a) experiment was calculated from data obtained using a point sampling method, whereas forb species abundance in 1999 was determined using the importance score method. The experiment consisted of different frequencies (annual, biennial and triennial) of burning and mowing in winter or spring in combination with different frequencies of summer mowing (none, early, late or both).Results: Grasses responded to the type of disturbance (burn or mow) and frequency of burning, whereas forbs responded primarily to the presence or absence of any form of disturbance and secondarily to the timing of burning (spring versus winter). Summer mowing and annual or biennial dormant‐period burning maintained communities dominated by short grasses, whereas tall grasses dominated under annual dormant‐period mowing, triennial burning or protection from disturbance. Grass tillering strategy (below‐ or above‐ground) influenced response to burning frequency. Many erect herbaceous dicot species with aerial meristems were reduced in abundance by summer mowing whereas most small creeping herbaceous dicot species appeared to be dependent upon summer mowing.Conclusions: This long‐term experiment demonstrated that: (1) grasses and forbs responded differently to burning and mowing; (2) simple plant traits, such as height, position of tiller initiation, and position of meristems have potential for predicting the response of species to the timing and frequency of burning and mowing.

堤防植生の刈り取りが カヤネズミ Ｍｉｃｒｏｍｙｓ ｍｉｎｕｔｕｓ の営巣に与える影響

Harvest mice build a nest with tall grasses, such as Common reed and Japanese pampas grass. Recently, their habitat has decreased and bank-grass mowing as river management seemed to affect on breeding of harvest mice. Grass mowing was set up in three different schedules in consideration of the harvest mouse in a bank of Kizu river; it carried out at intervals of two weeks from end of April. After the mowing, nesting distribution of harvest mouse and vegetation growth were investigated. At first, nests made of Common reed or Foxtail grass were found in the division of the mowing order, 50, 59 and 67 days after, respectively, then Common reed became main nest material. Nesting increased from May to September and breeding nests were built from July to September, a peak of breeding occurred in August. Since the average height of Common reed at the start of nesting was 120cm in all divisions, it was suggested that nesting is influenced by the height of vegetation. It turns out that the time of mowing have a great impact on the harvest mouse. Vegetation management which is necessary for a habitat of harvest mouse was discussed.

Long-term compositional responses of a South African mesic grassland to burning and mowing

Question: What is the long-term compositional response of grass and forb species to various combinations of burning and mowing? Can these responses be predicted from simple plant traits? Location: Ukulinga research and training farm (24°24'E, 30°24'S), Pietermaritzburg, KwaZulu-Natal, South Africa. Methods: Grass species relative abundance in 1996 in various burning and mowing treatments of a long-term (> 50 a) experiment was calculated from data obtained using a point sampling method, whereas forb species abundance in 1999 was determined using the importance score method. The experiment consisted of different frequencies (annual, biennial and triennial) of burning and mowing in winter or spring in combination with different frequencies of summer mowing (none, early, late or both). Results: Grasses responded to the type of disturbance (burn or mow) and frequency of burning, whereas forbs responded primarily to the presence or absence of any form of disturbance and secondarily to the timing of burning (spring versus winter). Summer mowing and annual or biennial dormantperiod burning maintained communities dominated by short grasses, whereas tall grasses dominated under annual dormant-period mowing, triennial burning or protection from disturbance. Grass tillering strategy (below- or above-ground) influenced response to burning frequency. Many erect herbaceous dicot species with aerial meristems were reduced in abundance by summer mowing whereas most small creeping herbaceous dicot species appeared to be dependent upon summer mowing. Conclusions: This long-term experiment demonstrated that: (1) grasses and forbs responded differently to burning and mowing; (2) simple plant traits, such as height, position of tiller initiation, and position of meristems have potential for predicting the response of species to the timing and frequency of burning and mowing.

The Use of Leaf Removal and Prohexadione-Ca to Modify `Camarosa' Strawberry Nursery Plant Morphology for Plasticulture Fruit Production

Our previous work on modifying strawberry plant morphology used either mowing to remove the leaf laminas and part of the petioles on `Camarosa', or a new reduced-risk gibberellin synthesis inhibitor, Prohexadione-Ca (ProCa), to restrict cell elongation in `Sweet Charlie'. These early studies showed promising results in acheiving desirable plant size and increasing fruit yield in annual hill plasticulture. Therefore, in the growing seasons of 2001 and 2002, we used `Camarosa' to explore the possibility of combining mowing and ProCa as a means of modifying strawberry transplant morphology in the nurseries, and studied its effect on fruit production in annual hill plasticulture. Plants were mowed and treated with 62.5 μL·L-1 of ProCa in a nursery field in Nova Scotia (45°26'N, 63°27'W). Treatments consisted of either mowing, the application of ProCa, or a combination of mowing and ProCa on one of two dates, 5 or 19 Sept. ProCa application early in the growing season had increased the production of daughter plants in the nursery. All plants were harvested in early October, and immediately transplanted in Dover, Fla. (28°00'N, 82°22'W). Fruits were collected twice weekly from late November to February or March. At time of harvest, both mowing and ProCa reduced plant height and total leaf area; plants which were treated with ProCa and mowed were the shortest. On average, treated plants had higher fruit yield as compared to untreated plants. In 2001, early fruit production in December was increased significantly in treated plants.

Effect of burning and mowing on grass and forb diversity in a long‐term grassland experiment

Abstract. Disturbance may be an important determinant of plant community composition and diversity owing to its effects on competitive interactions, resources, dominance and vigour. The effect of type, timing and frequency of disturbance on grass and forb species richness was examined using data from a long‐term (&gt; 50 yr) grassland burning and mowing experiment in KwaZulu‐Natal, South Africa.Grass species richness declined considerably (&gt; 50%) in the absence of disturbance, whereas forb species richness was unaffected. Annual burning in sites not mown in summer tended to increase grass species richness relative to triennial burning (22% increase) with the reverse being true in sites mown twice in summer (37% decline). Forb species richness declined by 25% in sites mown twice in summer relative to sites mown in early summer only. Disturbance was necessary to achieve maximum grass species richness presumably by removing litter and increasing the availability of light. The interaction of time of mowing in summer (early versus late) and time of burning during the dormant period (spring versus winter) had the most dramatic effect on species richness. Time of burning had no effect on richness in sites mown in early summer, but winter burning resulted in a dramatic decline (27–42%) in richness in sites mown in late summer. This effect may be related to possible greater soil desiccation with this combination of disturbances.