Influence of Insecticides and Reflective Mulch on Watermelon Vine Decline Caused by Squash vein yellowing virus (SqVYV)

2015 ◽  
Vol 16 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Chandrasekar S. Kousik ◽  
Scott Adkins ◽  
Craig G. Webster ◽  
William W. Turechek ◽  
Philip Stansly ◽  
...  
Keyword(s):  
Fruit Quality ◽  
Significant Interaction ◽  
Limiting Factor ◽  
Plastic Mulch ◽  
Central Florida ◽  
Chemical Treatments ◽  
The Past ◽  
Growing Seasons ◽  
Vine Decline ◽  
Yellowing Virus

Watermelon vine decline (WVD) caused by the whitefly-transmitted Squash vein yellowing virus (SqVYV) has been a serious limiting factor in watermelon production in southwest and west-central Florida over the past few years. Symptoms of WVD typically appear as sudden decline of vines a few weeks before harvest or just after the first harvest. Fruit symptoms include rind necrosis and flesh discoloration that affects fruit quality and marketability. The combination of insecticide treatments consisting of an imidacloprid drench (Admire Pro, 560 ml/ha) at transplanting followed by two foliar applications of spiromesifen (Oberon, 2SC, 490 ml/ha) and reflective plastic mulch was evaluated for management of WVD during fall growing seasons of 2006, 2007, and 2009. Virus inoculum source was introduced by planting SqVYV-infected squash plants at the ends of each plot. In all three experiments, the insecticide-treated plots had significantly lower levels of WVD on foliage and fruit compared to non-treated plots. In 2007, the reflective plastic mulch was effective in reducing foliar WVD compared to non-reflective mulch, but not in 2006 and 2009. No significant interaction between plastic mulch and chemical treatments was observed on WVD development on foliage or fruit. Our results suggest that application of insecticides for managing whiteflies can help manage SqVYV-caused WVD. Accepted for publication 13 January 2015. Published 25 March 2015.

scholarly journals Sources of Resistance in U.S. Plant Introductions to Watermelon Vine Decline Caused by Squash Vein Yellowing Virus

HortScience ◽  
2009 ◽  
Vol 44 (2) ◽  
pp. 256-262 ◽  
Author(s):  
Chandrasekar S. Kousik ◽  
Scott Adkins ◽  
William W. Turechek ◽  
Pamela D. Roberts
Keyword(s):  
Citrullus Lanatus ◽  
Field Trials ◽  
Limiting Factor ◽  
Sources Of Resistance ◽  
Central Florida ◽  
Plant Introductions ◽  
Disease Progress ◽  
Vine Decline ◽  
Moderate Resistance ◽  
Yellowing Virus

Watermelon vine decline (WVD) is a new and emerging disease caused by the whitefly-transmitted squash vein yellowing virus (SqVYV). The disease has become a major limiting factor in watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] production in southwest and west–central Florida and is estimated to have caused more than $60 million in losses. Symptoms of WVD typically occur at or just before harvest and are manifested as sudden decline of the vines, often with a reduction in fruit quality. In this study, we present results of greenhouse and field evaluations of U.S. plant introductions (PIs) for resistance to SqVYV. Of the 218 PIs we evaluated for resistance to SqVYV, none were completely immune, but several showed varying levels of resistance and these were further evaluated in two greenhouse and field trials. Disease progress was significantly slower on the selected PIs compared with disease progress on susceptible watermelon cultivars Mickey Lee and Crimson Sweet. Moderate resistance was observed in two C. colocynthis (PI 386015 and PI 386024), a Praecitrullus fistulosus (PI 381749), and two C. lanatus var. lanatus PIs (PI 482266 and PI 392291). Variability in the resistant reaction to SqVYV within most PIs was observed. The identification of potential sources of partial resistance to SqVYV suggests that watermelon germplasm with moderate resistance can be developed by careful screening and selection of individual resistant plants within these PIs for use in breeding programs.

First Report of Macrophomina phaseolina, Fusarium brachygibbosum, and Lasiodiplodia theobromae Causing Fungal Watermelon Vine Decline in Southwest and West-Central Florida

2021 ◽  
Author(s):  
Cristina Pisani ◽  
Scott Adkins ◽  
William W Turechek ◽  
Pragna C Patel ◽  
Erin Rosskopf
Keyword(s):  
Disease Severity ◽  
Fungal Pathogens ◽  
Disease Incidence ◽  
Macrophomina Phaseolina ◽  
Lasiodiplodia Theobromae ◽  
First Report ◽  
Central Florida ◽  
Untreated Check ◽  
Vine Decline ◽  
Yellowing Virus

Wilt and vine decline symptoms were observed on watermelon plants in Glades and Hardee Counties in Florida in spring 2017 that resembled viral watermelon vine decline caused by squash vein yellowing virus (SqVYV). When no SqVYV was detected, greenhouse studies and morphological and molecular analyses revealed three fungal pathogens, Macrophomina phaseolina, Fusarium brachygibbosum, and Lasiodiplodia theobromae, that were not previously reported on watermelon in Florida. A previously reported oomycete, Pythium spinosum, was also detected in some, but not all isolates, and but when applied independently, resulted in disease incidence that was comparable to the untreated check, ruling it out as a primary causal agent of the symptoms observed in the field. In one of three experiments, seedlings inoculated with a combination of Macrophomina phaseolina, Fusarium brachygibbosum, and Pythium spinosum suffered the highest disease severity based on AUDPC values. In another experiment, seedlings inoculated with F. brachygibbosum exhibited the most severe symptoms and rapid disease development following inoculation. When seeds were inoculated with either a single or a combination of the isolated fungi, those inoculated with L. theobromae resulted in seedlings with the greatest disease severity. This is the first report of these three fungal pathogens on watermelon in Florida.

scholarly journals Improving growth and productivity of tomato by some biostimulants and micronutrients with or without mulching

1970 ◽  
pp. 15-23
Author(s):  
M.N. Helaly, A.A. Arafa, Heba M. Ibrahim, K.H. Ghoniem
Keyword(s):  
Fruit Quality ◽  
Field Experiments ◽  
Total Yield ◽  
Fruit Weight ◽  
Seaweed Extract ◽  
Growth And Yield ◽  
Plastic Mulch ◽  
Tomato Crop ◽  
Growing Seasons ◽  
Black Plastic

Two field experiments were doled out during 2014 and 2015 growing seasons to assess tomato growth and yield as affected by some biostimulants and micronutrients with or without mulching type. Certain physiological characters were also examined, plant height, the number of branches per plant chlorophyll a, nitrogen %, red fruit weight and total yield per plant as well as fruit firmness and ascorbic acid concentration in fruit was increased in tomatoes under black plastic mulch compared with bar soil. Application of either biostimulants or micronutrient used to increase all growth and yield characters as well as photosynthetic pigments, ions percentage, and fruit quality. Additive effects were shown under mulching, seaweed extract proved to be the most effective in this respect. It could be recommended that spraying tomato crop at 35 and 50 days from transplanting with 500 mg/l seaweed extract under clear or black plastic mulch in order for inducing the highest yield and improve fruit quality.

scholarly journals Survey of Glyphosate-Resistant Junglerice Accessions in Dicamba-Resistant Crops in Tennessee

2020 ◽  
pp. 1-31
Author(s):  
Clay M. Perkins ◽  
Thomas C. Mueller ◽  
Lawrence E. Steckel
Keyword(s):  
Resistance Factor ◽  
Relative Resistance ◽  
Roundup Ready ◽  
The Past ◽  
Growing Seasons ◽  
The Poor

Abstract Junglerice has become a major weed in Tennessee cotton and soybean fields. Glyphosate has been relied upon to control these accessions over the past two decades but in recent years cotton and soybean producers have reported junglerice escapes after glyphosate + dicamba and/or clethodim applications. In the growing seasons of 2018 and 2019, a survey was conducted of weed escapes in dicamba-resistant crops. Junglerice was the most prevalent weed escape in these dicamba-resistant (Roundup Ready Xtend®) cotton and soybean fields in both years of the study. In 2018 and 2019, junglerice was found 76% and 64% of the time in dicamba-resistant cotton and soybean fields, respectively. Progeny from junglerice seeds collected during this survey was screened for glyphosate and clethodim resistance. Seventy percent of the junglerice accessions tested had an effective relative resistance factor (RRF) of 3.1 to 8.5 to glyphosate. In all, 13% of the junglerice accessions could no longer be effectively controlled with glyphosate. This research also showed that all sampled accessions could still be controlled with clethodim in a greenhouse environment but less control was observed in the field. These data would also suggest that another cause for the poor junglerice control is dicamba antagonizing the glyphosate and clethodim activity.

An integrated approach for tracking climate-driven changes in treeline environments on different time scales in the Valle d’Aosta, Italian Alps

The Holocene ◽  
2021 ◽  
pp. 095968362110259
Author(s):  
Anna Masseroli ◽  
Giovanni Leonelli ◽  
Umberto Morra di Cella ◽  
Eric P Verrecchia ◽  
David Sebag ◽  
...  
Keyword(s):  
Integrated Approach ◽  
Early Summer ◽  
Ice Age ◽  
Limiting Factor ◽  
Alpine Treeline ◽  
Growing Seasons ◽  
Direct Measurements ◽  
Soil Temperatures ◽  
Summer Temperatures ◽  
Local Station

Both biotic and abiotic components, characterizing the mountain treeline ecotone, respond differently to climate variations. This study aims at reconstructing climate-driven changes by analyzing soil evolution in the late Holocene and by assessing the climatic trends for the last centuries and years in a key high-altitude climatic treeline (2515 m a.s.l.) on the SW slope of the Becca di Viou mountain (Aosta Valley Region, Italy). This approach is based on soil science and dendrochronological techniques, together with daily air/soil temperature monitoring of four recent growing seasons. Direct measurements show that the ongoing soil temperatures during the growing season, at the treeline and above, are higher than the predicted reference values for the Alpine treeline. Thus, they do not represent a limiting factor for tree establishment and growth, including at the highest altitudes of the potential treeline (2625 m a.s.l.). Dendrochronological evidences show a marked sensitivity of tree-ring growth to early-summer temperatures. During the recent 10-year period 2006–2015, trees at around 2300 m a.s.l. have grown at a rate that is approximately 1.9 times higher than during the 10-year period 1810–1819, one of the coolest periods of the Little Ice Age. On the other hand, soils show only an incipient response to the ongoing climate warming, likely because of its resilience regarding the changeable environmental conditions and the different factors influencing the soil development. The rising air temperature, and the consequent treeline upward shift, could be the cause of a shift from Regosol to soil with more marked Umbric characteristics, but only for soil profiles located on the N facing slopes. Overall, the results of this integrated approach permitted a quantification of the different responses in abiotic and biotic components through time, emphasizing the influence of local station conditions in responding to the past and ongoing climate change.

scholarly journals The Effect of Weed Competition on Apple Fruit Quality

2017 ◽  
Vol 45 (1) ◽  
pp. 120-125 ◽  
Author(s):  
Ersin ATAY ◽  
Seckin GARGIN ◽  
Ahmet ESITKEN ◽  
N. Pinar GUZEL ◽  
A. Nilgun ATAY ◽  
...  
Keyword(s):  
Fruit Quality ◽  
Fruit Weight ◽  
Apple Orchard ◽  
High Density ◽  
Soluble Solids ◽  
Limiting Factor ◽  
Weed Competition ◽  
Soluble Solids Content ◽  
Solids Content ◽  
Potassium Magnesium

Orchard performance is influenced by weed competition. In this study, the effects of weed competition on nutrient contents, chemical and physical fruit quality properties were sought. The study was carried out in a high-density apple orchard (‘Golden Delicious’/M.9) over two consecutive growing seasons. The effect of weed competition was studied at three different levels: weak, moderate and strong. Fruit firmness, soluble solids content, macronutrients (such as nitrogen, potassium and calcium) and potassium+magnesium/calcium ratio in fruit were significantly affected by weed competition. Strong weed competition negatively affected soluble solids content and potassium+magnesium/calcium ratio. In both trial years, soluble solids content was significantly higher in weak weed competition. In the first year of the study, soluble solids content ranged between 13.77±0.06% (strong weed competition) and 15.20±0.10% (weak weed competition). In the following year, soluble solids content values were determined as 13.13±0.23% in strong weed competition and 13.83±0.21% in weak weed competition. Weak weed competition showed superiority for fruit weight and potassium+magnesium/calcium ratio. As a whole, this study indicates that insufficient weed control in tree rows might be a limiting factor for fruit quality in high-density apple orchards.

scholarly journals Modification and Validation of Priestley–Taylor Model for Estimating Cotton Evapotranspiration under Plastic Mulch Condition

2016 ◽  
Vol 17 (4) ◽  
pp. 1281-1293 ◽  
Author(s):  
Zhipin Ai ◽  
Yonghui Yang
Keyword(s):  
Air Temperature ◽  
Soil Heat Flux ◽  
Taylor Model ◽  
Taylor Coefficient ◽  
Plastic Mulch ◽  
Area Index ◽  
Modified Model ◽  
Growing Seasons ◽  
Balance Analysis ◽  
Evapotranspiration Estimation

Abstract Compared with more comprehensive physical algorithms such as the Penman–Monteith model, the Priestley–Taylor model is widely used in estimating evapotranspiration for its robust ability to capture evapotranspiration and simplicity of use. The key point in successfully using the Priestley–Taylor model is to find a proper Priestley–Taylor coefficient, which is variable under different environmental conditions. Based on evapotranspiration partition and plant physiological limitation, this study developed a new model for estimating the Priestley–Taylor coefficient incorporating the effects of three easily obtainable parameters such as leaf area index (LAI), air temperature, and mulch fraction. Meanwhile, the effects of plastic film on the estimation of net radiation and soil heat flux were fully considered. The reliability of the modified Priestley–Taylor model was testified using observed cotton evapotranspiration from eddy covariance in two growing seasons, with high coefficients of determination of 0.86 and 0.81 in 2013 and 2014, respectively. Then, the modified model was further validated by estimating cotton evapotranspiration under three fractions of mulch cover: 0%, 60%, and 100%. The estimated values agreed well with the measured values via water balance analysis. It can be found that seasonal variation of the modified Priestley–Taylor coefficient showed a more reasonable pattern compared with the original coefficient of 1.26. Sensitivity analysis showed that the modified Priestley–Taylor coefficient was more sensitive to LAI than to air temperature. Overall, the modified model has much higher accuracy and could be used for evapotranspiration estimation under plastic mulch condition.

scholarly journals EARLY SPRING APPLICATION OF AMINOETHOXYVINILGLYCINE (AVG) INCREASES FRUIT SET AND YIELD OF ‘ROCHA’ PEARS

2017 ◽  
Vol 39 (4) ◽  
Author(s):  
MATEUS DA SILVEIRA PASA ◽  
BRUNO CARRA ◽  
CARINA PEREIRA DA SILVA ◽  
MARLISE NARA CIOTTA ◽  
ALBERTO FONTANELLA BRIGHENTI ◽  
...  
Keyword(s):  
Fruit Quality ◽  
Fruit Set ◽  
Block Design ◽  
Quality Attributes ◽  
Fruit Weight ◽  
Early Spring ◽  
Full Bloom ◽  
Growing Seasons ◽  
Randomized Block Design ◽  
Return Bloom

ABSTRACT The low fruit set is one of the main factors leading to poor yield of pear orchards in Brazil. Ethylene is associated with abscission of flowers and fruitlets. Then, the application of ethylene synthesis inhibitors, such as AVG, is a potential tool to increase fruit set of pears. The objective of this study was to evaluate the effect of AVG, sprayed at different rates and timings, on fruit set, yield and fruit quality of ‘Rocha’ pear. The study was performed in a commercial orchard located in the municipality of São Joaquim, SC, during the growing seasons of 2014/2015 and 2015/2016. Plant material consisted of ‘Rocha’ pear trees grafted on quince rootstock ‘BA29’. AVG was tested at different rates (60 mg L-1 and 80 mg L-1) and timings [full bloom, one week after full bloom (WAFB), and two WAFB), either alone or in combination. The experiment was arranged in a randomized block design, with at least five single-tree replications. The fruit set, number of fruit per tree, yield, estimated yield, fruit weight, return bloom, and fruit quality attributes were assessed. Fruit set and yield were consistently increased by single applications of AVG at 60 and 80 mg L-1 at both one and two weeks after full bloom, without negatively affecting fruit quality attributes and return bloom.

scholarly journals Mustard Cover Crop Growth and Weed Suppression in Organic, Strawberry Furrows in California

HortScience ◽  
2018 ◽  
Vol 53 (4) ◽  
pp. 432-440 ◽  
Author(s):  
Eric B. Brennan ◽  
Richard F. Smith
Keyword(s):  
Cover Crops ◽  
Cover Crop ◽  
Sinapis Alba ◽  
Weed Suppression ◽  
Shoot Biomass ◽  
Plastic Mulch ◽  
Seeding Rate ◽  
Crop Cover ◽  
Cover Cropping ◽  
Growing Seasons

Strawberry (Fragaria ×ananassa Duch.) production in California uses plastic mulch–covered beds that provide many benefits such as moisture conservation and weed control. Unfortunately, the mulch can also cause environmental problems by increasing runoff and soil erosion and reducing groundwater recharge. Planting cover crops in bare furrows between the plastic cover beds can help minimize these problems. Furrow cover cropping was evaluated during two growing seasons in organic strawberries in Salinas, CA, using a mustard (Sinapis alba L.) cover crop planted at two seeding rates (1× and 3×). Mustard was planted in November or December after strawberry transplanting and it resulted in average densities per meter of furrow of 54 and 162 mustard plants for the 1× and 3× rates, respectively. The mustard was mowed in February before it shaded the strawberry plants. Increasing the seeding rate increased mustard shoot biomass and height, and reduced the concentration of P in the mustard shoots. Compared with furrows with no cover crop, cover-cropped furrows reduced weed biomass by 29% and 40% in the 1× and 3× seeding rates, respectively, although weeds still accounted for at least 28% of the furrow biomass in the cover-cropped furrows. These results show that growing mustard cover crops in furrows without irrigating the furrows worked well even during years with relatively minimal precipitation. We conclude that 1) mustard densities of ≈150 plants/m furrow will likely provide the most benefits due to greater biomass production, N scavenging, and weed suppression; 2) mowing was an effective way to kill the mustard; and 3) high seeding rates of mustard alone are insufficient to provide adequate weed suppression in strawberry furrows.

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