scholarly journals IMPROVED DOWNY MILDEW CONTROL IN WINE GRAPES WITH VOSSEN BLUE

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 605d-605
Author(s):  
Joseph A. Fiola ◽  
Gary C. Pavlis
Keyword(s):  
Downy Mildew ◽  
Disease Incidence ◽  
Total Yield ◽  
Economic Loss ◽  
Plasmopara Viticola ◽  
Wine Grapes ◽  
Incidence Data ◽  
Average Cluster ◽  
Grape Cultivars ◽  
Downy Mildew Disease

Downy Mildew, Plasmopara viticola, causes major damage and economic loss to many wine grape cultivars grown in the Northeast. The purpose of the experiment was to test the efficacy of Vossen Blue (VB; iron pigment) in association with fungicides for the control of Downy Mildew disease of wine grapes in New Jersey. The experimental plot was a planting of `Seyval Blanc' (5th leaf). Treatments (applied via back-pack sprayer) included no fungicide (control I), full fungicide (FF) (RCE commercial recs; control II), FF + 4%VB, FF + 8%VB, 8%VB, Half Rate Fungicide (HF) + 4%VB, HF + 8%VB. There were no significant differences between treatments for total yield, average cluster weight, average berry weight, Brix %, and pH. Spectrophotometric (Hunter's Lab) analysis of foliage samples revealed that leaf samples from the VB treatments had greater green color (correlate: increased chlorophyll). Analysis of subjective (1-9) disease incidence data: FF8 significantly lower disease score that FF; FF4, HF4, HF8, and FF no difference. Compared to normal full fungicide: superior Downy Mildew control was achieved by adding VB to full fungicide; equal control was achieved with half fungicide and VB.

scholarly journals 800 PB 080 IMPROVED DOWNY MILDEW CONTROL IN WINE GRAPES WITH VOSSEN BLUE

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 547g-547
Author(s):  
Gary C. Pavlis ◽  
Joseph A. Fiola
Keyword(s):  
Downy Mildew ◽  
Statistical Difference ◽  
Leaf Tissue ◽  
Economic Loss ◽  
Plasmopara Viticola ◽  
Experimental Plot ◽  
Wine Grapes ◽  
Yield Data ◽  
Grape Cultivars ◽  
Downy Mildew Disease

Downy Mildew, Plasmopara viticola, causes major damage and economic loss to many wine grape cultivars grown in the Northeast. The purpose of this experiment was to test the efficacy of Vossen Blue (VB; iron pigment) in association with fungicides for the control of Downy Mildew disease of wine grapes in New Jersey. The experimental plot was a planting of Chancellor (10th leaf). Treatments (applied via back-pack sprayer) included no fungicide (NF), full fungicide (FF) (RCE commercial recs. half fungicide (HF), FF + 8%VB (FF8), HF + 8% VB (HF8), 88V B. Subjective (l-9) disease score for leaf tissue showed no statistical difference between the FF, FF8, HF and HF8 treatments however all showed superior Downy Mildew control to the 8% VB and the no fungicide control. Yield data indicated that the FF8 treatment resulted in higher yield (p is ≤ 0.01) than FF, HF and HF8. The NF and 8VB treatments resulted in the lowest yield. Compared to normal full fungicide, superior Downy Mildew control on the fruit was achieved by adding VB to full fungicide. These results are consist with previous experiments conducted on Seyval Blanc.

scholarly journals Evaluation of a Disease Warning System for Downy Mildew of Grapes

Plant Disease ◽  
2000 ◽  
Vol 84 (5) ◽  
pp. 549-554 ◽  
Author(s):  
L. V. Madden ◽  
M. A. Ellis ◽  
N. Lalancette ◽  
G. Hughes ◽  
L. L. Wilson
Keyword(s):  
Linear Model ◽  
Downy Mildew ◽  
Environmental Conditions ◽  
Generalized Linear Model ◽  
Disease Incidence ◽  
Warning System ◽  
Plasmopara Viticola ◽  
Effective Control ◽  
Subsequent Infection ◽  
Grape Downy Mildew

An electronic warning system for grape downy mildew— based on models for the infection of leaves of Vitis lambrusca, production of sporangia by Plasmopara viticola in lesions, and sporangial survival—was tested over 7 years in Ohio. Grapevines were sprayed with metalaxyl plus mancozeb (Ridomil MZ58) when the warning system indicated that environmental conditions were favorable for sporulation and subsequent infection. Over the 7 years, plots were sprayed from one to four times according to the warning system, and from four to 10 times according to the standard calendar-based schedule (depending on the date of the initiation of the experiment). The warning system resulted in yearly reductions of one to six sprays (with median of three sprays). Disease incidence (i.e., proportion of leaves with symptoms) in unsprayed plots at the end of the season ranged from 0 to 86%, with a median of 68%. Incidence generally was very similar for the warning-system and standard-schedule treatments (median of 7% of the leaves with symptoms), and both of these incidence values were significantly lower (P < 0.05) than that found for the unsprayed control, based on a generalized-linear-model analysis. Simplifications of the disease warning system, where sprays were applied based only on the infection or sporulation components of the system, were also effective in controlling the disease, although more fungicide applications sometimes were applied. Effective control of downy mildew, therefore, can be achieved with the use of the warning system with fewer sprays than a with a standard schedule.

scholarly journals Isolation of Plasmopara viticola from Grapevine Leaves

Proceedings ◽  
2019 ◽  
Vol 29 (1) ◽  
pp. 34
Author(s):  
Camelia Ungureanu ◽  
Liliana Cristina Soare ◽  
Diana Vizitiu ◽  
Mirela Calinescu ◽  
Irina Fierascu ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Plasmopara Viticola ◽  
Grapevine Downy Mildew ◽  
Grapevine Leaves ◽  
Downy Mildew Disease

In order to test some biofungicides, the isolation of Plasmopara viticola was carried out.Plasmopara viticola is a fungus that causes the grapevine downy mildew disease [...]

scholarly journals Susceptibility of Cold-Climate Wine Grape Cultivars to Downy Mildew, Powdery Mildew, and Black Rot

Plant Disease ◽  
2017 ◽  
Vol 101 (7) ◽  
pp. 1077-1085 ◽  
Author(s):  
David S. Jones ◽  
Patricia S. McManus
Keyword(s):  
Powdery Mildew ◽  
Downy Mildew ◽  
Management Strategies ◽  
Plasmopara Viticola ◽  
Cold Climate ◽  
Black Rot ◽  
Wine Grape ◽  
Plant Host ◽  
Northern United States ◽  
Grape Cultivars

Lack of knowledge regarding the susceptibility of cold-climate hybrid wine grape cultivars may be leading to the overuse of fungicides and underutilization of plant host resistance to combat disease in the northern United States. To provide new insights on diseases of cold-climate cultivars and to update management recommendations, disease was evaluated in three vineyards containing eight cultivars that were not sprayed with fungicides in 2015 and 2016. Disease severity or incidence of downy mildew (Plasmopara viticola), powdery mildew (Erysiphe necator), and black rot (Guignardia bidwellii) were measured from bud break until 2 weeks after harvest. Cold-climate cultivars ranged widely in susceptibility to different diseases and, although several cultivars were relatively resistant to two diseases, no cultivar was highly resistant to all three diseases. Additionally, a difference between foliar and fruit susceptibility for all three diseases was noted in several cultivars. These data provide a foundation for developing low-spray and certified organic disease management strategies for cold-climate wine grape cultivars based on susceptibility to disease.

scholarly journals Salvia officinalis Extract Can Protect Grapevine Against Plasmopara viticola

Plant Disease ◽  
2010 ◽  
Vol 94 (5) ◽  
pp. 575-580 ◽  
Author(s):  
Silvia Dagostin ◽  
Tiziano Formolo ◽  
Oscar Giovannini ◽  
Ilaria Pertot ◽  
Annegret Schmitt
Keyword(s):  
Disease Control ◽  
Downy Mildew ◽  
Disease Incidence ◽  
Plasmopara Viticola ◽  
Salvia Officinalis ◽  
Promising Alternative ◽  
Rainy Period ◽  
Grapevine Downy Mildew ◽  
Progress Curve ◽  
High Level

The ability of sage (Salvia officinalis) extract to control grapevine downy mildew under greenhouse and field conditions was tested. The persistence and rainfastness of sage extract were also investigated. Sage extract provided a high level of sustained disease control in artificially inoculated, potted grapevine under greenhouse conditions. However, even small amounts of simulated rainfall (10 mm) significantly reduced efficacy of sage extract. In a field experiment in 2006, sage extract provided 94% reduction in disease incidence and 63% reduction in area under the disease progress curve for disease severity on berries and leaves, respectively, reaching a level of disease control not significantly different from that provided by copper hydroxide. In 2007, the sage extract provided only a partial reduction (less than 30%) of downy mildew on leaves, probably as a result of a long rainy period between two of the consecutive treatments. Overall, sage extract effectively controlled grapevine downy mildew and could be a promising alternative to copper in organic viticulture. However, the low rainfastness of this treatment adversely affected its efficacy.

scholarly journals Environmental Factors Affecting Rose Downy Mildew and Development of a Forecasting Model for a Nursery Production System

Plant Disease ◽  
2003 ◽  
Vol 87 (6) ◽  
pp. 732-738 ◽  
Author(s):  
B. J. Aegerter ◽  
J. J. Nuñez ◽  
R. M. Davis
Keyword(s):  
Downy Mildew ◽  
Negative Correlation ◽  
Disease Incidence ◽  
Environmental Parameters ◽  
Leaf Wetness ◽  
Cumulative Number ◽  
Weather Variables ◽  
Factors Affecting ◽  
Incidence Data ◽  
Nursery Production

The effect of various environmental parameters on rose downy mildew caused by Peronospora sparsa was determined under controlled conditions and in the field. In growth chambers, optimal temperatures for infection and colonization of rose leaves were 15 to 20°C and 20 to 25°C, respectively. At optimal temperatures, infection required only 2 h of leaf wetness, although disease severity increased significantly with an increasing duration of leaf wetness up to 10 h. Infection of leaves occurred at temperatures as low as 5°C with 8 h of leaf wetness. The latent period of infection varied from 4 to 7 days. Weather and disease incidence data collected from natural field epidemics were used in the development of a predictive model of rose downy mildew. Logistic regression was used to identify those weather variables that explained the largest portion of the variation in disease incidence. The optimum regression model incorporated three weather variables calculated as cumulative totals over the previous 10 days: (i) hours of leaf wetness when temperatures were less than 20°C (positive correlation); (ii) hours between 15 and 20°C (negative correlation); and (iii) hours when temperatures exceeded 30°C (negative correlation). The simplest model, which was also a good fit, included only the 10-day cumulative number of hours of leaf wetness. The critical number of hours of leaf wetness for disease development was an average of 8.4 h per day over 10 days.

scholarly journals Efficacy of fungicides in management of Downy mildew disease of Cucumber (Cucumis sativus L.) under open field conditions, in Dhading district of Nepal

2020 ◽  
Vol 3 (1) ◽  
pp. 240-252
Author(s):  
Shailesh Pandit ◽  
Hira Kaji Manandhar ◽  
Krishna Hari Dhakal ◽  
Sramika Rijal ◽  
Sandesh Bhandari ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Cucumis Sativus ◽  
Open Field ◽  
Disease Incidence ◽  
Block Design ◽  
Trichoderma Viride ◽  
Field Conditions ◽  
Verticillium Lecanii ◽  
Cucumis Sativus L ◽  
Downy Mildew Disease

Downy mildew (Pseudoperonospora cubensis) is one of the most important disease of cucumber under open field conditions. Hence, the experiment was conducted to study the efficacy of fungicides in management of downy mildew disease of cucumber (Cucumis sativus L.) under open field in Chauradi-7 Dhading during spring season, 2019. Bhaktapur local variety of cucumber was used for the study. The experiment was laid out in single factor randomized complete block design with four replications. Three different bio-fungicides; Trichoderma viride + Trichoderma harzianum, Bacillus subtilis, Verticillium lecanii and one chemical fungicide; Krilaxyl (metalaxyl 8% + mancozeb 64%) were used as treatments. Normal water spray served as control. It was observed that bio-fungicides had insignificant effect in controlling the downy mildew. Pathological observation such as disease incidence percentage, severity percentage and AUDPC in bio-fungicides treated plots were not significantly different from water-sprayed control plots. Similarly, biometric attributes such as number of fruit, length and diameter of fruit, weight of fruit were also non-significant. Krilaxyl resulted significant effect in controlling downy mildew, providing maximum disease reduction (37.48%-50.72%) with lowest disease incidence (1.25-61.25%) and lowest value of AUDPC (138.7). Krilaxyl treated plots had higher number of fruit (6), longer length of fruit (17.15-18.95), higher diameter of fruit (4.16- 4.45 cm) and higher weight of fruit (677 - 759 g). Hence, chemical fungicide Krilaxyl was found better for the management of downy mildew disease in open field cucumber cultivation. Further, researches on bio-fungicides, especially of native strains are required for best result.

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