scholarly journals Occurrence, development and natural enemies of Pemphigus spyrothecae (Homoptera, Pemphigidae)

2019 ◽  
Vol 48 (No. 6) ◽  
pp. 248-270 ◽  
Author(s):  
J. Urban
Keyword(s):  
Leaf Area ◽  
Natural Enemies ◽  
Populus Nigra ◽  
Mortality Factors ◽  
Area Reduction ◽  
Important Regulator ◽  
Pemphigus Spyrothecae ◽  
Housing Estates ◽  
Leaf Area Reduction ◽  
Hover Flies

In 2001, galls were analysed of Pemphigus spyrothecae Pass. taken in one- to three-week intervals from Populus nigra and P. nigra var. italica at 4 localities in Brno. Fundatrices matured in the first half of June and during the first half of summer produced about 50 offsprings. Virgines produced about 10 offsprings which grew up in winged sexuparae. The winged individuals started to occur in galls from the beginning of August. In galls with intact development, on average 500 aphids developed. Galls with intact development on P. nigra var. italica reached larger average dimensions and contained at least by 4% more aphids than galls on P. nigra. About 5% of fundatrices died already in the 1st instar and other 3 to 6% in higher instars by the beginning of reproduction. At localities under investigation, 7.5 to 39.0% of galls on P. nigra and 3.9 to 13.7% of galls on P. nigra var. italica were occupied by the fly Leucopis puncticornis Meig. (Chamaemyiidae). About 24.3 to 32.2% of galls on P. nigra and 23.3 to 49.3% of galls on P. nigra var. italica were occupied by the bug Anthocoris minki Dohrn (Anthocoridae). Hover flies Heringia heringi (Zett.) and Pipiza festiva Meig. (Syrphidae) killing aphids in 3.8 to 30.4% of galls on P. nigra and 6.5 to 6.8% of galls on P. nigra var. italica were an important regulator. In August (i.e. at the beginning of the formation of winged sexuparae), the majority of galls opened through primary slit-shaped or oval emergence holes. A part (7.8 to 19.5%) of galls with so far intact development, however, remained closed and all aphids contained in them died. Diseases (particularly mycoses) often participated in the accelerated dying of aphids. The effect of mortality factors on the gall size differentiation was evaluated in details. The galls do not cause any leaf area reduction. In the case of mass outbreak, they decrease decorativeness of poplars in street alleys. In August and September, liquid excrements fall out from the galls (honeydew) polluting the environment in villages and housing estates.

Relationship between sugar maple budburst phenology and pear thrips damage

1991 ◽  
Vol 21 (7) ◽  
pp. 1043-1048 ◽  
Author(s):  
T. E. Kolb ◽  
D. A. J. Teulon
Keyword(s):  
Leaf Area ◽  
Sugar Maple ◽  
Leaf Size ◽  
Common Garden ◽  
Area Reduction ◽  
The Relationship ◽  
Leaf Area Reduction ◽  
Oviposition Sites ◽  
Damage Symptoms ◽  
Budburst Phenology

The relationship between budburst phenology and damage by the pear thrips (Taeniothripsinconsequens (Uzel) (Thysanoptera: Thripidae)) to sugar maple (Acersaccharum Marsh.) foliage was investigated in two studies. In the first study, seedlings in cages were exposed to adult thrips at different stages of budburst. Compared with uninfested control seedlings, introduction of five adult thrips per bud reduced total leaf area and average leaf size, and caused chlorosis, tattering, and cupping of leaves. Leaf area reduction and damage symptoms were greater for seedlings exposed to thrips when leaf margins were first visible at the tip of the bud compared with earlier and later stages of budburst. In the second study, budburst date and number of thrips oviposition sites on leaves (an index of thrips activity) were measured in a common-garden test of maple saplings from open-pollinated families. Thrips activity was greater on early-breaking than late-breaking buds. Date of opening for these early-breaking buds coincided closely with peak capture of flying thrips. Both budburst date and number of oviposition sites on leaves differed among families. Sugar maple genotypes with late budburst escaped heavy thrips damage. The results indicate that timing of vegetative budburst in sugar maple can influence the degree of thrips damage.

scholarly journals Game browse and its impact on selected grain crops

2009 ◽  
Vol 55 (No. 5) ◽  
pp. 181-186 ◽  
Author(s):  
R. Cerkal ◽  
K. Vejražka ◽  
J. Kamler ◽  
J. Dvořák
Keyword(s):  
Leaf Area ◽  
Significant Influence ◽  
Spring Barley ◽  
Field Trials ◽  
Growth Stages ◽  
Plant Parts ◽  
Area Reduction ◽  
Mechanical Removal ◽  
The Impact ◽  
Leaf Area Reduction

This work presents the results of a survey that studied simulated plant browsing by herbivores. In 2004–2006, winter wheat, spring barley, and maize field trials were founded in order to monitor the impact of different levels of defoliation (leaf area reduction) on the yield and grain quality. The defoliation was carried out by means of mechanical removal of plant parts in the early growth stages. Selected qualitative parameters were determined in the harvested grain of wheat and barley. Statistically significant influence of leaf area reduction (LAR) on grain yield (decrease by 4–14%) was found only in maize in 2004. No statistically significant influence of the leaf area reduction on thousand grain weight (TGW) was found in any of the studied crops. The leaf area reduction in barley did not affect grain characteristics; however, it had a statistically significant influence on the quality of wheat grain. Moreover, wheat reduction statistically significantly increased the falling number (by 29–39 s) and decreased SDS test values (by 8–9 ml).

The effect of fire severity and salvage logging traffic on regeneration and early growth of aspen suckers in north-central Alberta

2004 ◽  
Vol 80 (2) ◽  
pp. 251-256 ◽  
Author(s):  
Erin Fraser ◽  
Simon Landhäusser ◽  
Victor Lieffers
Keyword(s):  
Leaf Area ◽  
Populus Tremuloides ◽  
Negative Impact ◽  
Fire Severity ◽  
Trembling Aspen ◽  
North Central ◽  
Salvage Logging ◽  
Logging Damage ◽  
Area Reduction ◽  
Leaf Area Reduction

Density and growth of trembling aspen (Populus tremuloides Michx.) were measured in the first two years following wildfire to determine the effects of: 1) fire severity and 2) salvage logging damage on sucker regeneration. Results indicate that stand leaf area was not affected by fire severity, although the greatest number of suckers was produced following high severity burns. In contrast, plots with the highest level of machine disturbance in the salvage-logging study had 60% fewer suckers compared to the non-trafficked plots. These suckers tended to be smaller and had less leaf area than the non-trafficked plots, resulting in a stand leaf area reduction of up to 75%. This suggests that salvage logging could have a negative impact on the future growth and productivity of regenerating aspen stands. Key words: trembling aspen, regeneration, suckering, leaf area, wildfire, fire severity, salvage logging, machine traffic

scholarly journals Effect of Minicutting Length and Leaf Area Reduction on Growth and Nutritional Status of Eucalypt Propagules

ISRN Forestry ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-6
Author(s):  
Reynaldo Campos Santana ◽  
Sula Janaina Oliveira Fernandes ◽  
Miranda Titon ◽  
Aloisio Xavier ◽  
Priscila Fernandes de Souza ◽  
...  
Keyword(s):  
Nutritional Status ◽  
Leaf Area ◽  
Block Design ◽  
Nutritional Condition ◽  
Eucalyptus Urophylla ◽  
Area Reduction ◽  
Randomized Block Design ◽  
Proper Size ◽  
Leaf Area Reduction

Significant improvements to the technique of minicutting Eucalyptus clones have been reported in the literature. However, despite these recent efforts, studies addressing the proper size of minicuttings and the reduction of leaf area have not been well explored. Thus, the present study had the objective of evaluating the effects of the length of the minicuttings and the leaf area reduction on the growth and nutritional condition of Eucalyptus urophylla during propagation. The experiment was conducted for 90 days in the Plantar Reforestation Co. Nursery in the municipality of Curvelo, MG, using a randomized block design with 4 replicates in a 4×2×2 factorial arrangement. The effects of 4 lengths of minicuttings (4, 6, 8, and 10 cm), 2 levels of leaf area reductions (0 and 50%), and 2 commercial clones were studied. The length of the minicuttings and the reduction of leaf area did not affect the nutritional status of the leaves, nor did the length affect the quality of the plants at the age of 90 days. The results indicate that it is unnecessary to reduce the leaf area for Eucalyptus propagation.

scholarly journals The effect of leaf area reduction on the yield and quality of sugar beet (Beta vulgaris L. var. altissima Döll).

2007 ◽  
Vol 55 (5) ◽  
pp. 37-44 ◽  
Author(s):  
Radim Cerkal ◽  
Jan Dvořák ◽  
Karel Vejražka ◽  
Jiří Kamler
Keyword(s):  
Sugar Beet ◽  
Leaf Area ◽  
Sugar Content ◽  
Amino Nitrogen ◽  
Root Production ◽  
Root Yield ◽  
Area Index ◽  
Area Reduction ◽  
Leaf Area Reduction

The yield of sugar beet is directly affected by LAI (leaf area index) and values of LAD (leaf area duration). The integral leaf area plays, except for other factors, an important role during the damage or reduction of leaf apparatus. There are many sources of leaf damage: natural disasters (hailstorm), diseases, pests (including game browsing) etc. The intensity of the root production and quality differs in relation to the growth stage of the damage plant. The aim of this study was to evaluate the extent of losses in the root yield and the quality of sugar beet upon gradual reduction of the leaf area. Two diploid varieties Monza and Compact were used in the small-plot trials conducted in years 2004 to 2006 (in the experimental station Žabčice – maize production region, zone K2, average altitude 184 m, soil type was classified as gley fluvisoil, soil is medium heavy to heavy, clay-loam to loam type). The leaf area was manually reduced by 25% and 50% at BBCH 18–19 growth phase (8–9 leaves unfolded). The results were statistically evaluated by analysis of variance and testing by Tukey test (at the significance level α = 5%). Reduction of the leaf area was reflected on the decrease of the root yield by 1 to 10% depending on the year of harvest. In addition, the stressful state of the plants after defoliation resulted in the decrease of the yield of polarization sugar per hectare, namely by 0.45 to 1.66 t.ha–1. In 2005, the leaf area reduction caused a rise of the α-amino nitrogen content. The rise in the potassium and sodium cations content caused by the leaf area reduction also increased the sugar content in the treacle (by 0.1 to 0.16%). The increasing leaf area reduction lead to decreasing of yield of polarization sugar. However, this descent was statistically significant in harvest year 2006 only.

scholarly journals Photosynthetic Compensation to Partial Leaf Area Reduction in Sour Cherry

1992 ◽  
Vol 117 (2) ◽  
pp. 279-286 ◽  
Author(s):  
Desmond R. Layne ◽  
J.A. Flore
Keyword(s):  
Leaf Area ◽  
Leaf Surface ◽  
Sour Cherry ◽  
Dry Weight ◽  
Threshold Level ◽  
Prunus Cerasus ◽  
Area Reduction ◽  
Whole Plant ◽  
Leaf Surface Area ◽  
Leaf Area Reduction

The leaf surface area of l-year-old, potted `Montmorency' sour cherry (Prunus cerasus L.) trees was reduced by punching disks from some or all leaves to determine the threshold level of leaf area removal (LAR) necessary to reduce net CO2 assimilation (A) and whole-plant growth. Removal of 30% of the leaf area of individual leaves reduced A on a whole-leaf basis between 1 and 3 weeks following LAR. Less than 30% LAR was compensated for by higher estimated carboxylation efficiency and ribulose-l,5-bisphosphate (RuBP) regeneration capacity. The threshold level of LAR based on gas exchange of individual leaves was 20%. Although whole-plant dry weight accumulation was reduced at all levels of LAR, a disproportionately large decrease in dry weight occurred as LAR increased from 20% to 30%. This result indicates that 30% LAR exceeded the threshold LAR level that was noted for A (20% LAR). Wound ethylene production induced by leaf-punching ceased after 24 hours, which indicated that wounds had healed and that ethylene, therefore, did not influence A significantly. The observed threshoId of 20% LAR represents a significant compensation ability for sour cherry, but this threshold may change with crop load, environment, or both.

scholarly journals Relationship between the Effects of Salinity on Seedling Leaf Area and Fruit Yield of Six Muskmelon Cultivars

HortScience ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 642-644 ◽  
Author(s):  
José A. Franco ◽  
Juan A. Fernández ◽  
Sebastián Bañón ◽  
Alberto González
Keyword(s):  
Salt Tolerance ◽  
Leaf Area ◽  
Control Level ◽  
Selection Criterion ◽  
Relative Yield ◽  
Rapid Screening ◽  
Area Reduction ◽  
Field Culture ◽  
Leaf Area Reduction ◽  
Seedling Leaf

Six muskmelon (Cucumis melo L.) Galia-type cultivars (`Delada', `Gallicum', `Galor', `Melina', `Regal' and `Revigal') were tested for salt tolerance at the seedling stage and during growth in the field. Three levels of salinity (ECW 2.5 (control), 5.0 and 7.5 dS·m-1), established by adding NaCl to fresh water, were used. The effect of salinity on seedling growth was assessed by measuring the total leaf area 36 days after sowing. `Melina' was the most tolerant at this stage and during subsequent growth in field, with a relative seedling leaf area of 60 and a relative yield of 66 at 7.5 dS·m-1 salinity, both expressed as a percentage of the values obtained at the control level of salinity. `Delada' was the most sensitive to the highest level of salinity at both stages, with relative seedling leaf area and yield of 51 and 56, respectively. For all cultivars, a highly significant correlation (r = 0.99) was established between the influence of salinity on seedling leaf area reduction and on decrease in yield during field culture. The results indicate that the reduction in seedling leaf area can be a good selection criterion to facilitate rapid screening for salt tolerance in muskmelon.

Sign in / Sign up

Export Citation Format

Share Document