scholarly journals Effect of Urea, CaCO3, and Dolomite on Pseudothecial Development and Ascospore Production of Mycosphaerella citri

Plant Disease ◽  
2003 ◽  
Vol 87 (5) ◽  
pp. 478-483 ◽  
Author(s):  
S. N. Mondal ◽  
L. W. Timmer
Keyword(s):  
Leaf Litter ◽  
Laboratory Experiments ◽  
Leaf Decomposition ◽  
Incidence Density ◽  
Effect Of Treatment ◽  
Integrated Program ◽  
Ascospore Production

Citrus greasy spot, caused by Mycosphaerella citri, produces lesions on leaves, followed by premature defoliation, and rind blotch on fruit. Ascospores produced in leaf litter represent the major source of inoculum. The effect of treatment of leaf litter with urea, CaCO3, or dolomite on the development of pseudothecia and ascospore production was evaluated. In laboratory experiments, one urea application reduced production of pseudothecia and ascospores by up to 90%, but did not affect time of production of pseudothecia or ascospores or rate of leaf decomposition. Two applications of urea delayed leaf decomposition. As the rates of CaCO3 or dolomite were increased, pseudothecial incidence, density, time to ascospore production, and total numbers of ascospores decreased and the rate of leaf compostion increased. Immature pseudothecia on leaves treated with urea or CaCO3 degenerated and produced fewer ascospores per pseudothecium. The results observed in microplot studies in the field were similar to those observed in laboratory experiments. The number of days to pseudothecia and ascospore production and the pseudothecial incidence and density were negatively related to the rate of CaCO3 or dolomite applied. Application of CaCO3 dolomite, or urea to leaf litter can reduce inoculum and be useful in an integrated program of greasy spot management.

The importance of shredding caddis larvae (Trichoptera: Limnephilidae) in leaf litter breakdown

Zoosymposia ◽  
2019 ◽  
Vol 14 (1) ◽  
pp. 39-53
Author(s):  
MARTA GELLERT ◽  
KATARZYNA KWIATKOWSKA ◽  
JANUSZ MAJECKI
Keyword(s):  
Leaf Litter ◽  
Laboratory Experiments ◽  
Quercus Rubra ◽  
Alnus Glutinosa ◽  
Leaf Decomposition ◽  
Acer Pseudoplatanus ◽  
Breakdown Rate ◽  
Caddisfly Larvae ◽  
Four Square ◽  
Fallen Leaves

In field and laboratory experiments, we assessed the role of caddisfly larvae in leaf decomposition occurring in headwaters with a focus on the breakdown of alien Quercus rubra leaves. A field experiment was conducted at two sites: in Wolbórka Spring and 150 m downstream. Eight 0.5 x 0.5 m “mats” were constructed. 1m2 of one type of fallen leaves: Quercus robur, Acer pseudoplatanus, Quercus rubra and Alnus glutinosa was placed in each mat. The caddisfly assemblages on the leaf mats consisted of 550 shredder larvae and 394 predatory larvae of Plectrocnemia conspersa. Among the 4 shredder species in both years, the larvae of P. nigricornis dominated on all leaf species at both sites. In the laboratory experiment, ten Vth instar larvae of Potamophylax nigricornis were placed in to each of four square (30 x 30 cm) boxes containing 500 cm2 of Q. robur, A. pseudoplatanus, Q. rubra and A. glutinosa leaves. The length of time of leaf decomposition was measured in the laboratory. The fastest loss of leaf surface was noted with respect to A. glutinosa (in the field as well as in the laboratory). Shredders collected from Q. rubra mats were numerous and the breakdown rate of leaf litter in the field as well as in the laboratory experiments was similar to Q. robur and A. pseudoplatanus. The number of caddis corresponded with the time of decomposition, which in 2014 was 20 days shorter than in 2013.

scholarly journals Comparative Studies on the Effect of Adjuvants with Urea to Reduce the Overwintering Inoculum of Venturia inaequalis

Plant Disease ◽  
2019 ◽  
Vol 103 (3) ◽  
pp. 531-537 ◽  
Author(s):  
Janna Beckerman ◽  
Chelsi Abbott
Keyword(s):  
Leaf Litter ◽  
Litter Decomposition ◽  
Comparative Studies ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Organic Surfactant ◽  
Comparable Performance ◽  
Improved Sanitation ◽  
Litter Degradation ◽  
Ascospore Production

A 2-year study on the use of organic and conventional adjuvants alone, or mixed with urea, was conducted for management of overwintering inoculum of the apple scab pathogen, Venturia inaequalis. Select adjuvants (LI 700, Bond Max, Latron B-1956, and Organic Wet Betty [OWB]) have the potential to hasten urea-driven leaf litter decomposition and reduce V. inaequalis overwintering inoculum comparable to urea, and that one organic surfactant could perform the same level of leaf decomposition as urea. Combinations of adjuvants with urea significantly improved leaf litter degradation compared with urea alone, concomitant with reducing the number of pseudothecia present and pseudothecium fertility. We demonstrate that the combination of urea with Bond Max or OWB reduced pseudothecia fertility and ascospore production to less than 5% in the remaining pseudothecia, a significantly greater reduction than with urea alone. These results suggest that conventional growers combine urea with Bond Max or OWB to more effectively reduce overwintering inoculum, and that the adjuvant OWB can provide organic growers with comparable performance to urea used in conventional orchards for improved sanitation.

scholarly journals Leaf litter as a possible food source for chironomids (Diptera) in Brazilian and Portuguese headwater streams

2007 ◽  
Vol 24 (2) ◽  
pp. 442-448 ◽  
Author(s):  
Marcos Callisto ◽  
José F. Gonçalves Jr ◽  
Manuel A. S. Graça
Keyword(s):  
Leaf Litter ◽  
Riparian Vegetation ◽  
Laboratory Experiments ◽  
Food Source ◽  
Alnus Glutinosa ◽  
Chironomid Larvae ◽  
Feeding Experiments ◽  
Chironomid Species ◽  
Consumption Rates ◽  
Potential Use

Our objective was to evaluate the potential use of leaf detritus by chironomid larvae. Field and laboratory experiments were performed using leaves and chironomid species collected in Portugal and Brazil. Laboratory experiments under controlled conditions were done using microbial conditioned senescent leaves of Alnus glutinosa (L.) Gaertn, Neriumoleander L., Protium heptaphilum (Aubl.) March, Protium brasiliense (Spreng) Engl., Myrcia guyanensis(Aubl.) DC and Miconia chartacea Triana. Laboratory experiments were performed using specimens collected from leaf litter in local streams. Whenever possible, after the experiments, chironomids were allowed to emerge as adults and identified. In Portugal the following taxa were identified: Micropsectra apposita (Walker, 1856), Polypedilum albicorne (Meigen, 1838),Eukiefferiella claripennis Lundbeck (1898), Rheocricotopus (Psilocricotopus) atripes Rempel (1937) and Ablabesmyia Johannsen (1905) (Diptera, Chironomidae). Consumption rates ranged from 0.15 ± 0.10 mg (AFDM) of leaf animal-1 day-1 (Micropsectra apposita feeding on Alnus glutinosa) up to 0.85 ± 0.33 mg (AFDM) of leaf animal-1 day-1 (Polypedilum albicorne feeding on Miconia chartacea). In Brazil, the following taxa were identified from leaves: Phaenopsectra sp., Chironomus spp. and Polypedilum sp. and maximum consumption rates reached 0.47 ± 0.28 (AFDM) of leaf mg.animal-1.day-1 (Chironomus Meigen (1803) feeding on Protium heptaphilum). Feeding experiments with laboratory cultured specimens, revealed that some chironomids were unable to feed on decomposing leaves (e.g., C. xanthus Rempel (1939) on P.brasiliensis and M.guyanensis). Our results suggest that some stream chironomids (not typical shredders) can use leaf litter of riparian vegetation as a complementary food source.

Food preferences of the estuarine crab Sesarma catenata estimated through laboratory experiments

2015 ◽  
Vol 66 (8) ◽  
pp. 750 ◽  
Author(s):  
Leandro Bergamino ◽  
Nicole B. Richoux
Keyword(s):  
Leaf Litter ◽  
Laboratory Experiments ◽  
Trophic Ecology ◽  
Food Preferences ◽  
Feeding Preference ◽  
Mature Leaves ◽  
Feeding Experiments ◽  
Riparian Trees ◽  
Consumption Rates ◽  
Potential Food

Feeding by sesarmid crabs on plants represents an important energy pathway within some estuarine ecosystems. We examined the trophic ecology of estuarine sesarmid crabs Sesarma catenata through a series of laboratory feeding-preference experiments. Our experiments considered decomposed and mature leaves of terrestrial riparian trees, marsh plants Chenolea diffusa and Sarcocornia perennis and the marshgrass Spartina maritima as potential food items. S. catenata preferred decomposed leaves of terrestrial riparian trees, followed by decomposed and mature leaves of S. maritima. We suggest that the low carbon:nitrogen (C:N) ratios of S. maritima and high bacterial production associated with decomposed terrestrial leaves may explain the trophic behaviour of S. catenata. The faecal production by S. catenata during these experiments confirmed the preferential assimilation of decomposed material by the crabs. By combining the consumption rates with an estimated density of S. catenata within the local estuary that it inhabits, we suggest that moderate proportions of the leaf material can potentially be consumed by this species (34% of total leaf litter), leaving substantial amounts of unconsumed leaf litter that may represent an important subsidy for adjacent environments. Our results validate previously published trophic data, showing the value of linking feeding experiments with biological tracers to improve food-web models.

scholarly journals Modelling Inoculum Availability of Plurivorosphaerella nawae in Persimmon Leaf Litter with Bayesian Beta Regression

2020 ◽  
Author(s):  
Joaquín Martínez-Minaya ◽  
David V Conesa ◽  
Antonio López-Quílez ◽  
Jose Luís Mira ◽  
Antonio Vicent
Keyword(s):  
Leaf Litter ◽  
Fixed Effects ◽  
Plant Pathogens ◽  
Random Effect ◽  
Absolute Error ◽  
Beta Regression ◽  
Diospyros Kaki ◽  
Modeling Framework ◽  
Fungal Plant Pathogens ◽  
Ascospore Production

Circular leaf spot (CLS), caused by Plurivorosphaerella nawae, is a serious disease affecting persimmon (Diospyros kaki) that induces necrotic lesions on leaves, defoliation and fruit drop. Under Mediterranean conditions, P. nawae forms pseudothecia in the leaf litter during winter and ascospores are released in spring infecting susceptible leaves. Persimmon growers are advised to apply fungicides for CLS control during the period of inoculum availability, which was defined based on ascospore counts under the microscope. A model of inoculum availability of P. nawae was developed and evaluated as an alternative to ascospore counts. Leaf litter samples were collected weekly in L’Alcúdia (Spain) from 2010 to 2015. Leaves were soaked, placed in a wind tunnel, and the ascospores of P. nawae released were counted. Hierarchical Bayesian beta regression methods were used to model the dynamics of ascospore production in the leaf litter. The selected model included accumulated degree days (ADD) and ADD taking into account the vapor pressure deficit (ADDvpd) as fixed effects, and year as random effect. This model had a mean absolute error of 0.042 and a root mean square error of 0.062. The beta regression model was evaluated in four orchards from 2010 to 2015. Higher accuracy was obtained at the beginning and the end of the ascospore production period, which are the events of interest to schedule fungicide sprays for CLS control in Spain. This same modeling framework can be extended to other fungal plant pathogens whose inoculum dynamics are expressed as proportion data.

scholarly journals Decomposition of Entandrophragmacylindricum Tree Prunings in Agroforestry System in Onne, Rivers State

2021 ◽  
pp. 87-93
Author(s):  
Koyejo A.O ◽  
Olatidoye O.R ◽  
Adetunji A.S
Keyword(s):  
Leaf Litter ◽  
Fertility Restoration ◽  
Block Design ◽  
Soil Surface ◽  
Agroforestry System ◽  
Leaf Decomposition ◽  
High Rate ◽  
Research Station ◽  
Swamp Forest ◽  
Rivers State

A study was conducted at Swamp Forest Research Station, Onne, Forestry Research Institute of Nigeria, to evaluate the rate of decomposition of E. cylindricumtree prunings. The experiment was a 2x8 factorial in a randomized complete block design with three replications. The first factor comprises two placement methods (surface-placed and soil-incorporated) and the second factor comprises eight biweekly sampling intervals (2 – 16 weeks). The litterbag technique was employed. Results indicated that the Total leaf decomposition (100.0%) of soil incorporated leaf litter was obtained at 16th week after litter placement (WALP). Soil-surface placed had 98.00% at 16th WALP. Leaf half-lives of the soil-surface placed and soil incorporated were 5.08 and 2.10 WALP respectively. The turnover coefficients (k1) of the soil surface-placed and soil -incorporated leaf litter of E. cylindricum were 6.93yr-1 and 17.33 yr-1 respectively. The high rate of fresh leaf decomposition and subsequent release of nutrient make E. cylindricum leaf pruning a good source of organic manure for soil fertility restoration.

scholarly journals Modelling Inoculum Availability of Plurivorosphaerella nawae in Persimmon Leaf Litter with Bayesian Beta Regression

2019 ◽  
Author(s):  
Joaquín Martínez-Minaya ◽  
David Conesa ◽  
Antonio López-Quílez ◽  
José Luis Mira ◽  
Antonio Vicent
Keyword(s):  
Leaf Litter ◽  
Fixed Effects ◽  
Plant Pathogens ◽  
Random Effect ◽  
Beta Regression ◽  
Diospyros Kaki ◽  
Modelling Framework ◽  
Fungal Plant Pathogens ◽  
Serious Disease ◽  
Ascospore Production

AbstractCircular leaf spot (CLS), caused by Plurivorosphaerella nawae, is a serious disease of persimmon (Diospyros kaki) inducing necrotic lesions on leaves, defoliation and fruit drop. Under Mediter-ranean conditions, P. nawae forms pseudothecia in the leaf litter during winter and ascospores are released in spring infecting susceptible leaves. Persimmon growers are advised to apply fungicides for CLS control during the period of inoculum availability, which was defined based on ascospore counts under the microscope. A model of inoculum availability of P. nawae was developed and evaluated as an alternative to ascospore counts. Leaf litter samples were collected weekly in L’Alcúdia from 2010 to 2015. Leaves were soaked, placed in a wind tunnel, and released ascospores of P. nawae were counted. Hierarchical Bayesian beta regression methods were used to fit the dynamics of ascospore production in the leaf litter. The selected model, having the lowest values of DIC, WAIC and LCPO, included accumulated degree days (ADD) and ADD taking into account the vapor pressure deficit (ADDvpd) as fixed effects, and year as a random effect. This model had a MAE of 0.042 and RMSE of 0.062. The beta regression model was evaluated in four orchards for different years from 2010 to 2015. Higher accuracy was obtained at the beginning and the end of the ascospore production period, which are the events of interest to schedule fungicide sprays for CLS control in Spain. This same modelling framework can be extended to other fungal plant pathogens whose inoculum dynamics are expressed as proportion data.

Tree species mediated effects on leaf litter dynamics in pure and mixed stands of oak and beech

2008 ◽  
Vol 38 (3) ◽  
pp. 528-538 ◽  
Author(s):  
Mathieu Jonard ◽  
Frederic Andre ◽  
Quentin Ponette
Keyword(s):  
Mass Loss ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Leaf Litter ◽  
Tree Species ◽  
Litter Quality ◽  
Leaf Decomposition ◽  
Mixed Stands ◽  
Stand Type

This study aimed to evaluate the relative importance of the factors whereby tree species composition can influence leaf litter dynamics. Leaf litter production and chemical composition were measured in pure and mixed stands of oak ( Quercus petraea Liebl.) and beech ( Fagus sylvatica L.). Pure and mixed leaf litter of both species were incubated in each stand type to assess separately the environmental, litter quality, and litter mixture effects on decomposition. To better understand the environmental effects, ground climate was measured in the different stands and the effects of soil water content on decomposition were evaluated using roofs to simulate drought conditions. Although total leaf litter amounts were not affected by stand composition, leaf decomposition varied with litter quality and with the environmental conditions. In the same environment, oak leaf litter disappeared on average 1.7 times faster than beech leaf litter. Decomposition of oak leaves increased significantly in the mixed-species litterbags. In contrast, the overall mass loss of the mixed litter tallied with the mass loss estimated by examining the decomposition of the component litter separately (additive-effect hypothesis). The effects of stand type appeared in the third year of incubation: leaf mass loss of both species was greater in the beech stand. In addition, soil water content affected leaf decomposition: the oak and beach leaf mass losses dropped by 24% and 17%, respectively, in the dry modality.

scholarly journals Epidemiology and Control of Citrus Greasy Spot in Different Citrus-Growing Areas in Florida

Plant Disease ◽  
2000 ◽  
Vol 84 (12) ◽  
pp. 1294-1298 ◽  
Author(s):  
L. W. Timmer ◽  
P. D. Roberts ◽  
H. M. Darhower ◽  
P. M. Bushong ◽  
E. W. Stover ◽  
...  
Keyword(s):  
Leaf Litter ◽  
East Coast ◽  
Effective Control ◽  
Central Florida ◽  
Southwest Florida ◽  
Time Of Application ◽  
Trap Plants ◽  
Copper Fungicide ◽  
And Control ◽  
Ascospore Production

Greasy spot, caused by Mycosphaerella citri, causes defoliation and yield losses on grapefruit in all areas of Florida, but is more severe in southwest Florida and the east coast than in central Florida. The amount of leaf litter, numbers of ascospores produced, and severity of greasy spot on trap plants were monitored throughout 1997 and 1998 in Immokalee (southwest Florida) and Lake Alfred (central Florida). Leaf litter and ascospore production were greatest from March to July in both locations, with little litter and few ascospores thereafter. Ascospore production occurred earlier in Immokalee than in Lake Alfred in both years. Disease on trap plants was moderate to severe throughout the year except from November to February. Large numbers of ascospores produced early in the year when conditions were less favorable resulted in the same disease severity levels as low numbers of ascospores produced later in the year when environmental conditions were favorable. Greater greasy spot severity in southwest Florida, compared with central Florida, is more likely due to higher rainfall and warmer winter temperatures than to differences in time of infection. Single annual copper fungicide applications were made each month from April to August in 1998 and 1999 in LaBelle (southwest Florida), Ft. Pierce (east coast), and Lake Alfred to determine the most effective time of application. Two two-spray treatments, May + July and June + August, were also evaluated in 1999. A single copper fungicide application in June provided the most consistently effective control across all locations. The June + August two-spray treatment was very effective in disease control, but usually no better than a well-timed single application.

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