scholarly journals Optimum timing of fungicides for control of onion white rot (Sclerotium cepivorum)

2008 ◽  
Vol 61 ◽  
pp. 393-393 ◽  
Author(s):  
J.L. Tyson ◽  
R.A. Fullerton ◽  
R.W. Chynoweth ◽  
P.A. Rheinlander ◽  
G.N. Hill
Keyword(s):  
Disease Onset ◽  
White Rot ◽  
Optimal Timing ◽  
Base Temperature ◽  
Degree Days ◽  
Poor Control ◽  
Sclerotium Cepivorum ◽  
Application Analysis ◽  
Soil Temperatures ◽  
Accumulated Degree Days

Onion white rot caused by Sclerotium cepivorum continues to be a major fungal disease of onions in New Zealand The onset of the disease in the Pukekohe area can be predicted by the use of cumulative average daily soil temperatures above a base temperature (white rot degree days) This prediction model was used to determine the optimal timing for fungicide application Analysis of data from trials on timing of fungicide applications conducted between 19892007 showed a correlation between the efficacy of fungicide programme and accumulated degree days with later start times in relation to disease onset equating to a consistent drop in efficacy The disease normally occurs when white rot degree days reach 250 Fungicide programmes commenced above this value achieved relatively poor control Spray programmes should start before the disease is observed in the field with start times between 100 and 200 white rot degree days achieving the best control

scholarly journals Creation and Validation of a Temperature-Based Phenology Model for Meloidogyne incognita on Common Bean

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 240
Author(s):  
Ariadna Giné ◽  
Patricia Monfort ◽  
Francisco Javier Sorribas
Keyword(s):  
Life Cycle ◽  
Meloidogyne Incognita ◽  
Egg Production ◽  
Thermal Constant ◽  
Base Temperature ◽  
Degree Days ◽  
Thermal Requirements ◽  
Soil Temperatures ◽  
Phenology Model ◽  
Accumulated Degree Days

The thermal requirements of Meloidogyne incognita on Phaseolus vulgaris in a set of constant soil temperatures were determined and the phenology model was validated at fluctuating soil temperatures. The base temperature (Tb) and the thermal constant (S) from nematode inoculation to females starting to lay eggs were 11.3 °C and 323 accumulated degree days (DD), respectively; Tb = 10.5 °C and S = 147 DD from egg production to emergence of juveniles; and Tb = 11.1 °C and S = 476 DD for life cycle completion. At fluctuating soil temperatures in pots with the minimum lower than Tb and the maximum higher than To (optimal temperature), the DD calculation was carried out by the average daily temperature–Tb (ADTb) and the single sine method over Tb (SSTb) with horizontal, intermediate, and vertical cutoffs. The most accurate were the ADTb and the SSTb with horizontal and intermediate cutoffs (93–106% of the predicted value) but the vertical underestimated the accumulated DD (75–82% of the predicted value). When fluctuating soil temperatures were between Tb and To in a plastic greenhouse, only the ADTb method was used. Life cycle completion was observed around 465 DD (accuracy between 0.95 and 0.99) at four different transplanting dates.

scholarly journals Spatial Soil Temperature and Moisture Monitoring Across the Transylvanian Plain in Romania

2010 ◽  
Vol 67 (1) ◽  
Author(s):  
Beatrix HAGGARD ◽  
Teodor RUSU ◽  
David WEINDORF ◽  
Horea CACOVEAN ◽  
Paula MORARU ◽  
...  
Keyword(s):  
Best Management Practices ◽  
Management Practices ◽  
Spline Interpolation ◽  
Planting Date ◽  
Growing Degree Days ◽  
Base Temperature ◽  
Degree Days ◽  
Corn Hybrids ◽  
Important Region ◽  
Soil Temperatures

The Transylvanian Plain, Romania is an important region for agronomic productivity. However, limited soils data and adoption of best management practices hinder land productivity. Soil temperatures of the Transylvanian Plain were evaluated using a set of twenty datalogging stations positioned throughout the plain. Soil temperatures were monitored at the surface and at 10, 30, and 50 cm depths, and soil moisture was monitored at 10 cm. Preliminary results indicate that most soils of the Transylvanian Plain will have a mesic temperature regime. However, differences in seasonal warming and cooling trends across the plain were noted. These have important implications for planting recommendations. Growing degree days (GDDs) are preferred over maturity ratings, because they can account for temperature anomalies. The crop being considered for this study was corn. The base temperature (BT) was set at 10oC, and the upper threshold was 30oC. Two methods were used to calculate GDDs; 1) minimum and maximum daily temperatures, and 2) 24 h of averaged temperature data. Growing degree days were run from 110-199 day of year (DOY) to represent approximate planting date to tasseling. The DOY that 694 accumulated growing degree days (AGDDs) was reached at each site was then analyzed to identify differences across the TP. Three sites failed to reach 694 AGDDs by DOY 199, and were excluded from comparisons to other results. Averaged values were used to create spline interpolation maps with ArcMap 9.2 (ESRI, Redlands, CA, USA). The southeastern portion of the TP was found to tassel a month earlier assuming a planting date of 109 DOY. Four DeKalb® corn hybrids were then selected based on GDDs to tasseling, drydown, drought tolerance, and insect resistance. With a better understanding of the GDD trends across the TP, more effective planting and harvesting could be accomplished by Romanian farmers to maximize agronomic production.

A TEMPERATURE-DEPENDENT MODEL OF EGG DEVELOPMENT OF THE WESTERN CORN ROOTWORM, DIABROTICA VIRGIFERA VIRGIFERA LECONTE (COLEOPTERA: CHRYSOMELIDAE)

1991 ◽  
Vol 123 (6) ◽  
pp. 1183-1197 ◽  
Author(s):  
A.W. Schaafsma ◽  
G.H. Whitfield ◽  
C.R. Ellis
Keyword(s):  
Simulation Model ◽  
Diabrotica Virgifera Virgifera ◽  
Base Temperature ◽  
Diabrotica Virgifera ◽  
Degree Days ◽  
Egg Development ◽  
Egg Hatch ◽  
Developmental Threshold ◽  
Soil Temperatures ◽  
Developmental Rates

AbstractDevelopmental rates of post-diapause eggs of Diabrotica virgifera virgifera LeConte were compared in the laboratory at six constant temperatures, 12, 16, 20, 24, 28, and 32°C. Linear and nonlinear models were fitted to temperature versus developmental data and were used to predict egg hatch in the field. A four-parameter model fitted to median developmental rates (r2 = 0.99) indicated that development was linear between 16 and 28°C, optimal at 28°C, and decreased at 32°C. The lower development threshold (± SE) (10.5 ± 0.1°C) was determined by linear regression and the x-intercept method. Completion of post-diapause egg development required 258 ± 3 degree-days (± SE) above the base temperature. This compared well with the mean degree-days accumulated to 50% hatch (± SE) of 265 ± 24 which we observed in the field at several locations over 3 years using a degree-day model incorporating an 11°C developmental threshold and soil temperatures at 5- and 10-cm depths. A stochastic simulation model, incorporating a nonlinear developmental function dependant on soil temperatures taken every 2 h also predicted 50% hatch within 2 days. This model was validated in the field with 19 independent records of soil temperatures for several locations at two depths in the soil over 3 years. The simulation model accurately predicted time of 5 and 95% hatch, which indicates that this model has broad application in predicting the pattern of egg hatch for pest management.

scholarly journals Use of Belowground Growing Degree Days to Predict Rooting of Dormant Hardwood Cuttings of Populus

2004 ◽  
Vol 53 (1-6) ◽  
pp. 154-160 ◽  
Author(s):  
R. S. Zalesny ◽  
E. O. Bauer ◽  
D. E. Riemenschneider
Keyword(s):  
Populus Deltoides ◽  
Dry Weight ◽  
Growing Degree Days ◽  
Base Temperature ◽  
Degree Days ◽  
Planting Dates ◽  
Growing Period ◽  
Period 2 ◽  
Soil Temperatures ◽  
Total Dry Weight

Abstract Planting Populus cuttings based on calendar days neglects soil temperature extremes and does not promote rooting based on specific genotypes. Our objectives were to: 1) test the biological efficacy of a thermal index based on belowground growing degree days (GDD) across the growing period, 2) test for interactions between belowground GDD and clones, and 3) identify beneficial planting windows based on combinations of genotypes and belowground GDD. We tested two clones of Populus deltoides Bartr. ex Marsh (D133, D134) and four hybrid clones of P. deltoides × P. maximowiczii A. Henry (DM101, DM105, NC14105, NC14107). Cuttings, 20 cm long, were planted in randomized complete blocks at 15- × 15-cm spacing across three planting dates during 1999 at Alexandria, Minnesota, USA (45.9°N, 95.4°W) and Fertile, Minnesota, USA (47.3°N, 96.2°W). Temperatures at 20 cm belowground were converted to GDD with a base temperature of 10°C. We measured root, top, and total dry weight, along with number of roots after 14 d of growth. Relatively warmer and cooler soil temperatures promoted rooting for the cottonwoods and hybrids, respectively. We recommend planting after reaching a threshold of 163 belowground GDD for P. deltoides clones and planting before reaching a threshold of 173 belowground GDD for P. deltoides × P. maximowiczii clones.

scholarly journals Influence of Various Polyethylene Mulch Colors on Growth and Development of `Vates' Collards

HortScience ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 600D-600
Author(s):  
J.M Kemble ◽  
J. Brown ◽  
E. Simonne
Keyword(s):  
Growth And Development ◽  
Soil Depth ◽  
Dry Weight ◽  
Base Temperature ◽  
Fresh Weight ◽  
Degree Days ◽  
Marketable Yield ◽  
Soil Temperatures ◽  
Polyethylene Mulch ◽  
Final Harvest

The effect of various mulch colors (black, yellow, red, blue, white, and aluminum) on growth and development of `Vates' collards was evaluated in Fall 1996 at the E.V. Smith Research Center in Shorter, Ala. Black polyethylene mulch was installed onto raised, fumigated beds, then sprayed with a 1: 2 (v/v) mixture of exterior oil-based enamel paint to paint thinner with one of the five mulch colors listed. Five-week-old plants were transplanted into beds. Beginning two weeks after transplanting and continuing every other week thereafter, heads were harvested to determine head fresh weight and dry weight. Hourly soil temperatures at 10 cm soil depth were recorded and growing degree days (GDDs) with a base temperature of 4.4 °C were calculated. At two weeks after transplanting, average head fresh and dry weight were highest for the aluminum-colored treatment with head fresh (24.7 and 12.3 g, respectively) and dry weights (2.7 and 1.3 g, respectively) twice that of the yellow treatment (P ≤ 0.05). By four weeks after transplanting and up through the final harvest, marketable yield and average head fresh weights did not differ among the treatments (17,900 kg/ha, 1.4 kg per head, respectively). The red and black mulch treatments accumulated more GDDs than the other treatments, but total marketable yields did not differ among any treatments.

scholarly journals A Heat Unit Model to Predict Growth and Development of Muskmelon (Cucumis melo var. reticulatus Naud.) to Anthesis

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 790D-790
Author(s):  
S. Jenni ◽  
D.C. Cloutier ◽  
G. Bourgeois ◽  
K.A. Stewart
Keyword(s):  
Cucumis Melo ◽  
Dry Weight ◽  
Base Temperature ◽  
Degree Days ◽  
Heat Unit ◽  
Air Temperatures ◽  
Unit Model ◽  
Dependent Variables ◽  
Soil Temperatures ◽  
Unit Formula

Plant dry weight of muskmelon transplants to anthesis could be predicted from a multiple linear regression based on air and soil temperatures prevailing under 11 mulch and rowcover combinations. The two dependent variables of the regression model consisted of a heat unit formula for air temperatures with a base temperature of 14C and a maximum-reduced threshold at 40C, and a standard growing-degree-day formula for soil temperatures with a base temperature of 12C. Based on 2 years of data, 86.5% of the variation in the dry weight (on a log scale) could be predicted with this model. The base temperature for predicting time to anthesis of muskmelon transplants was established at 6.8C and the thermal time ranged between 335 and 391 degree-days during the 2 years of the experiment.

THE DIURNAL AND SEASONAL PATTERN OF HATCHING OF WINTER MOTH EGGS, OPEROPHTERA BRUMATA (GEOMETRIDAE: LEPIDOPTERA)

1970 ◽  
Vol 102 (6) ◽  
pp. 759-768 ◽  
Author(s):  
D. G. Embree
Keyword(s):  
Seasonal Pattern ◽  
Early Spring ◽  
Threshold Temperature ◽  
Base Temperature ◽  
Degree Days ◽  
Operophtera Brumata ◽  
Winter Moth ◽  
Lower Base ◽  
Best Estimate ◽  
Accumulated Degree Days

AbstractWinter moth hatching begins daily at approximately 0645 hours A.S.T. both in the field during the normal hatching season and in the laboratory during the winter. This diurnal pattern is not related to temperature or light and appears to be intrinsic.The seasonal rate of hatching in the spring was related to accumulated heat. Eggs first exposed to cold December temperatures then stored at 35°F (1.7 °C) until early spring, were incubated at a series of controlled temperatures. The theoretical threshold temperature of development was determined as 41°F (5 °C). Accumulated degree-days based on this threshold did not give the best estimate of the time of hatching in the field where temperatures, because they were recorded in Stevenson’s screens (meteorological cabinets), were generally lower than those at the egg sites. The best estimate was obtained by using a lower base temperature of 39°F (3.9 °C) which compensated for differences in temperature between Stevenson screens and egg sites. Mean hatch in the field occurred when accumulated degree-days reached 292.A predictive curve is presented which predicted the date of mid-hatch of the winter moth to within 1 to 2 days over a 9-year period.

scholarly journals Flatheaded Apple Tree Borer (Coleoptera: Buprestidae) in Nursery-Grown Red Maples: Phenology of Emergence, Treatment Timing, and Response to Stressed Trees

1988 ◽  
Vol 6 (1) ◽  
pp. 18-22 ◽  
Author(s):  
Daniel A. Potter ◽  
G. Mark Timmons ◽  
F. Carter Gordon
Keyword(s):  
Apple Tree ◽  
Acer Rubrum ◽  
Base Temperature ◽  
Red Maple ◽  
Single Application ◽  
Degree Days ◽  
Treatment Timing ◽  
Forecasting System ◽  
C 50 ◽  
Accumulated Degree Days

Emergence of adult flatheaded apple tree borers, Chrysobothris femorata (Olivier), from red maple (Acer rubrum L.) trees and cut bolts was monitored in central Kentucky from 1984–1986. A forecasting system based on accumulated degree-days (DD) was developed for predicting optimum treatment dates. Date of first emergence ranged from May 8 to June 6, corresponding to a mean accumulation of 412 Centigrade DD (742 F DD) calculated from a base temperature of 10°C (50°F). A single application of lindane or chlorpyrifos applied soon after adult borers began to emerge protected young red maple trees from infestation. Adult C. femorata were trapped in nurseries from May until August. Twenty-five species of adult Buprestidae representing 5 genera were attracted to experimentally stressed red maples. Although results were variable, stressed trees were generally more attractive and/or susceptible to borers.

scholarly journals Potential and actual ascospore release of Erysiphe necator chasmothecia in Austria

2020 ◽  
Author(s):  
M. Redl ◽  
L. Sitavanc ◽  
B. Spangl ◽  
S. Steinkellner
Keyword(s):  
Environmental Influence ◽  
Disease Onset ◽  
Bud Break ◽  
Degree Days ◽  
Weather Factors ◽  
Erysiphe Necator ◽  
Factors Affecting ◽  
Total Potential ◽  
Ascospore Release ◽  
Accumulated Degree Days

Abstract Ascospores of grape powdery mildew (Erysiphe necator Schw.) play a crucial role in the disease onset in spring in many vine-growing areas. We investigated the physiological maturation of chasmothecia and the time of the first potential ascospore release in three grape-growing areas in Austria by providing standardized conditions for ascospore release in the laboratory and excluding the environmental influence for the release itself. In the overwintering season 2017/2018, the potential ascospore release started in March 2018 in all three investigated wine-growing areas, while in 2018/19, the potential ascospore release was already possible in autumn 2018. Autumn 2018 was characterized by higher temperatures than autumn 2017. We related accumulated degree days (base 8 °C) after chasmothecia formation with the time of first potential chasmothecia dehiscence and found that more than 480 degree days are necessary to reach physiological maturity of chasmothecia. Temperature significantly influenced the dynamics of the potential of ascospore release. More than 50% of the total potential of ascospore release occurred before bud break in both years. Furthermore, weather factors affecting the actual ascospore release in the field were studied. Precipitation and leaf wetness showed a significant positive correlation with ascospore release in the vineyard. In contrast to the potential release, only a small percentage of actual release in the field occurred before bud break, while 84 and 95% of total trapped ascospores were found between bud break and flowering in 2018 and 2019, respectively. Our results reveal that the potential release and actual release have to be combined to predict ascospore release in spring.

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