scholarly journals Curative Fungicide Activity Against Calonectria pseudonaviculata, the Boxwood Blight Pathogen1

2020 ◽  
Vol 38 (2) ◽  
pp. 44-49
Author(s):  
J. A. LaMondia
Keyword(s):  
Disease Management ◽  
Leaf Area ◽  
Post Infection ◽  
Untreated Control ◽  
Post Inoculation ◽  
Diseased Leaf ◽  
Green Mountain ◽  
Thiophanate Methyl ◽  
Detached Leaves ◽  
Fungicide Activity

Abstract Azoxystrobin, azoxystrobin plus benzovindiflupyr, kresoxim-methyl, propiconazole, pyraclostrobin, pyraclostrobin plus fluxapyroxad, tebuconazole, tetraconazole, thiophanate-methyl, and triflumizole fungicides were evaluated for curative and anti-sporulant activity against boxwood blight caused by Calonectria pseudonaviculata on detached leaves and whole boxwood plants (Buxus spp.). Pretreating detached leaves with 30 or 300 ppm a.i. 24 h prior to inoculation reduced disease compared to the untreated control for all fungicides. Fungicides were also applied 24 to 96 h post-inoculation. Only propiconazole reduced diseased leaf incidence to at least half of the control. When leaves were treated post-infection with 300 ppm propiconazole, tetraconazole, tebuconazole, or triflumizole, the pathogen did not sporulate over 2 wks. Propiconazole also reduced the percent of leaf area diseased; lesions were nearly 80% smaller with 300 ppm applied 48 h after inoculation. ‘True Dwarf' boxwood plants treated with 450 ppm thiophanate-methyl, 120 ppm pyraclostrobin or 150 ppm propiconazole 48 h after inoculation demonstrated that only propiconazole reduced the number of diseased leaves, blight lesions and the frequency of pathogen re-isolation. Experiments with ‘Green Mound' and ‘Green Mountain' boxwood cultivars and additional fungicides applied 48 h after inoculation demonstrated that propiconazole at 300 ppm, pyraclostrobin plus fluxapyroxad (150 ppm each) and azoxystrobin (135 ppm) plus benzovindiflupyr (67.5 ppm) reduced disease. Index words: fungicide management, Buxus, chemical disease management Chemicals used in this study: azoxystrobin (Heritage 50 WG), azoxystrobin plus benzovindiflupyr (Mural 30, 50 WG), kresoxim-methyl (Cygnus 50 WG), propiconazole (ProCon-Z 14.3 L), pyraclostrobin (Insignia 20 WG), pyraclostrobin plus fluxapyroxad (Orkestra Intrinsic 21.26 SC), tebuconazole (Torque 38.7 SC), tetraconazole (Minerva 11.6 SC), thiophanate-methyl (3336 50% WP), triflumizole (Procure 480 SC). Species used in this study: boxwood (Buxus L.), boxwood blight (Calonectria pseudonaviculata (Crous, J.Z. Groenew. & C.F. Hill) L. Lombard, M. J. Wingf. & Crous.

scholarly journals Differences in Leaf Cuticle Structure and Efficacy among Eastern Redbud and Mexican Redbud Phenotypes

1995 ◽  
Vol 120 (1) ◽  
pp. 59-64 ◽  
Author(s):  
Jimmy L. Tipton ◽  
Marcia White
Keyword(s):  
Leaf Area ◽  
Water Loss ◽  
Loss Rate ◽  
Dry Mass ◽  
Abaxial Surface ◽  
Cercis Canadensis ◽  
Area Basis ◽  
Detached Leaves ◽  
Eastern Redbud ◽  
Mass Basis

The objective of this study was to compare the structure and efficacy in terms of retarding cuticular transpiration of leaf cuticles from eastern redbud (Cercis canadensis L.) and dull-leaf and glossy-leaf Mexican redbud [Cercis canadensis var. mexicana (Rose) M. Hopk.]. Leaves of Mexican redbud exhibited several xeromorphic characteristics compared to eastern redbud: a smaller, thicker leaf with thicker cuticles, more cuticular wax, a higher specific leaf mass, and greater hydrated water content on a leaf area basis. Mexican redbuds with a glossy leaf differed from those with a dull leaf only in a thicker adaxial cuticle lacking wax crystallite on the surface. Epicuticular wax crystallite were present on the abaxial surface of all leaves examined. Detached leaves of eastern redbud had a higher water loss rate than those of Mexican redbud only on a dry mass basis, not on a leaf area basis. There was no difference in the rate of water loss by detached leaves of glossy-leaf and dull-leaf Mexican redbuds after 4 hours.

scholarly journals Digital processing of leaf area of soybeans, subjected to different treatments of seeds

2020 ◽  
Vol 13 (3) ◽  
pp. 24
Author(s):  
M. L. V. Passos ◽  
J. B. C. Souza ◽  
E. A. Silva ◽  
C. A. A. C. Silva ◽  
W. S. Sousa ◽  
...  
Keyword(s):  
Image Processing ◽  
Computer Program ◽  
Leaf Area ◽  
Seed Treatment ◽  
Digital Camera ◽  
Digital Processing ◽  
Thiophanate Methyl ◽  
Beneficial Effects ◽  
Non Destructive

Digital image processing, when applied to the study of leaf area, allows the integration of the direct measurement and non-destructive, and thus preserves the integrity of the plant. The objective was the quantification of the leaf area of soybean, cv. FTS Paragominas RR, submitted to different treatments of seed with the use of the computer program ImageJ, and basic presuppositions of image processing. The experiment was conducted at the Center of Agrarian Sciences and Environmental, Federal University of Maranhão, in Chapadinha (MA), in the period from February to June 2018. The seeds of soybean 'Paragominas RR' were submitted to the technique of seed treatment, consisting of three fungicides of the active ingredients, thiophanate methyl + fluazinam, fludioxonil and carbendazim + tiram, an insecticide active ingredient fipronil and the control. The leaf area was analyzed in the growth phase, through the use of digital camera and ImageJ®. The use of the routines in the computer program ImageJ® were effective for the determination of leaf area of the soybean submitted to different treatments of the seed. The thiophanate methyl + fluazinam in the dose 200 mL per 100 kg of seeds showed beneficial effects on growth of the cv. FTS Paragominas RR, as estimated by the leaf area.

A simple and low-cost method for leaf area measurement of detached leaves

1997 ◽  
Vol 33 (01) ◽  
pp. 65-72 ◽  
Author(s):  
J. T. Korva ◽  
G. A. Forbes
Keyword(s):  
Solanum Tuberosum ◽  
Leaf Area ◽  
Low Cost ◽  
Electronic Equipment ◽  
New Method ◽  
Area Measurement ◽  
Water Spray ◽  
Spray Method ◽  
Detached Leaves ◽  
Highly Correlated

A technique for leaf area measurement utilizing water spray as an inexpensive substitute for electronic equipment was developed and tested with leaves of potato (Solanum tuberosum L.). The leaf areas measured by the spray method were highly correlated with those measured by an electronic area meter. Measurements of leaf area obtained by the spray method were significantly more highly correlated with those obtained by the area meter than were the measurements of dry weights. The main advantages of the new method are precision, accuracy and immediate results at a low cost.

scholarly journals Field Characterization of Partial Resistance to Gray Leaf Spot in Elite Maize Germplasm

2020 ◽  
Vol 110 (10) ◽  
pp. 1668-1679
Author(s):  
James O. Nyanapah ◽  
Patrick O. Ayiecho ◽  
Julius O. Nyabundi ◽  
Washington Otieno ◽  
Peter S. Ojiambo
Keyword(s):  
Disease Resistance ◽  
Leaf Area ◽  
Plant Development ◽  
Leaf Spot ◽  
Partial Resistance ◽  
Inflection Point ◽  
Inbred Lines ◽  
Gray Leaf Spot ◽  
Diseased Leaf ◽  
Diseased Leaf Area

Forty-eight inbred lines of maize with varying levels of resistance to gray leaf spot (GLS) were artificially inoculated with Cercospora zeina and evaluated to characterize partial disease resistance in maize under field conditions from 2012 to 2014 across 12 environments in western Kenya. Eight measures of disease epidemic—that is, final percent diseased leaf area (FPDLA), standardized area under the disease progress curve (SAUDPC), weighted mean absolute rate of disease increase (ρ), disease severity scale (CDSG), percent diseased leaf area at the inflection point (PDLAIP), SAUDPC at the inflection point (SAUDPCIP), time from inoculation to transition of disease progress from the increasing to the decreasing phase of epidemic increase (TIP), and latent period (LP)—were examined. Inbred lines significantly (P < 0.05) affected all measures of disease epidemic except ρ. However, the proportion of the variation attributed to the analysis of variance model was most strongly associated with SAUDPC (R2 = 89.4%). Inbred lines were also most consistently ranked for disease resistance based on SAUDPC. Although SAUDPC was deemed the most useful variable for quantifying partial resistance in the test genotypes, the proportion of the variation in SAUDPC in each plot was most strongly (R2 = 93.9%) explained by disease ratings taken between the VT and R4 stages of plant development. Individual disease ratings at the R4 stage of plant development were nearly as effective as SAUDPC in discerning the differential reaction of test genotypes. Thus, GLS rankings of inbred lines based on disease ratings at these plant developmental stages should be useful in prebreeding nurseries and preliminary evaluation trials involving large germplasm populations.

scholarly journals Water and Soil Nutrient Dynamics of Huanglongbing-Affected Citrus Trees as Impacted by Ground-Applied Nutrients

Agronomy ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1485 ◽  
Author(s):  
Alisheikh A. Atta ◽  
Kelly T. Morgan ◽  
Said A. Hamido ◽  
Davie M. Kadyampakeni ◽  
Kamal A. Mahmoud
Keyword(s):  
Leaf Area ◽  
Sap Flow ◽  
Untreated Control ◽  
Soil Nutrient ◽  
Irrigation Scheduling ◽  
Summer Season ◽  
Stem Water Potential ◽  
Area Index ◽  
Available N ◽  
Citrus Trees

The decrease in the rate of inflow and outflow of water—and thereby the uptake of plant nutrients as the result of Huanglongbing (HLB or citrus greening)—leads to a decline in overall tree growth and the development of nutrient deficiencies in HLB-affected citrus trees. This study was conducted at the University of Florida, Southwest Florida Research and Education Center (SWFREC) near Immokalee, FL from January 2017 through December 2019. The objective of the study was to determine the effect of rootstocks, nutrient type, rate, and frequency of applications on leaf area index (LAI), water relations (stomatal conductance [gs], stem water potential [Ψw], and sap flow), soil nutrient accumulation, and dynamics under HLB-affected citrus trees. The experiment was arranged in a split-split plot design that consisted of two types of rootstocks, three nitrogen (N) rates, three soil-applied secondary macronutrients, and an untreated control replicated four times. LAI significantly increased in response to the secondary macronutrients compared with uncontrolled trees. A significantly greater gs, and thus a decline in Ψw, was a manifestation of higher sap flow per unit LA (leaf area) and moisture stress for trees budded on Swingle (Swc) than Cleopatra (Cleo) rootstocks, respectively. The hourly sap flow showed significantly less water consumption per unit LA for trees that received a full dose of Ca or Mg nutrition than Ca + Mg treated and untreated control trees. The soil nutrient concentrations were consistently higher in the topmost soil depth (0–15 cm) than the two lower soil depths (15–30 cm, 30–45 cm). Mobile nutrients: soil nitrate–nitrogen (NO3-N) and Mg2+ Mg2+, Mn2+, Zn2+, and B leached to the lower soil (15–30 cm) depth during the summer season. However, the multiple split applications of N as Best Management Practices (BMPs) and optimum irrigation scheduling based on reference evapotranspiration (ETo) maintained soil available N (ammonium nitrogen [NH4-N] and NO3-N) below 4.0 mg kg−1, which was a magnitude 2.0–4.0× less than the conventional N applications. Soil NH4-N and NO3-N leached to the two lower soil depths during the rainy summer season only when trees received the highest N rate (280 kg ha−1), suggesting a lower citrus N requirement. Therefore, 224 kg ha−1 N coupled with a full Ca or Mg dose could be the recommended rate for HLB-affected citrus trees.

scholarly journals Abundance, damage severity and management of guava mealybug, ferrisia virgata ckll

2019 ◽  
Vol 16 (2) ◽  
pp. 73-82
Author(s):  
MMH Khan
Keyword(s):  
Relative Humidity ◽  
Leaf Area ◽  
Negative Correlation ◽  
Untreated Control ◽  
Soap Solution ◽  
Maximum Temperature ◽  
Water Spray ◽  
Positive Correlation ◽  
Middle Leaf ◽  
Percent Mortality

The research was carried out to know the abundance and damage severity of mealybug on sarupkathi variety of guava and to evaluate the efficacy of jet powder and Fighter 2.5EC for suppressing populations of mealybug during January to October 2014. Results revealed that the highest number of guava mealybug was observed on middle leaf (42/leaf) while the lowest number was on lower leaf (13/leaf). The highest percent leaf area covered by mealybug was found on middle leaf (78%) while the lowest was on fruit (18%). Maximum temperature and relative humidity had a positive correlation on the mealybug population while the rainfall showed a negative correlation. The highest percent mortality was observed in T2 treatment (Jet powder applied @ 5.0 g L-1 of water) at 24 HAT (hours after treatment) (86.05%) and 48 HAT (93.83%), respectively. At 72 HAT, the highest percent mortality was observed T3 treatment (Jet powder applied @ 7.5 g L-1 of water). In case of insecticidal control, the highest percent mortality was observed in T2 (100%) and T3 (100%) treatments, respectively followed by T1 (98.03%) at 24 HAT. Similar trends were also observed among all treatments at 48 HAT and 72 HAT, respectively. No significant differences were found among three doses of Fighter 2.5EC. The lowest percent mortality of mealybug population was found in T4 (Water spray forcibly) at 24 HAT, 48 HAT and 72 HAT, respectively. No mortality was recorded in untreated control at different HAT in both application of soap solution and insecticides. SAARC J. Agri., 16(2): 73-82 (2018)

EFFECTS OF BENOMYL AND TWO RELATED SYSTEMIC FUNGICIDES ON GROWTH OF FUSARIUM WILT-SUSCEPTIBLE AND RESISTANT MUSKMELON

1972 ◽  
Vol 52 (5) ◽  
pp. 775-779 ◽  
Author(s):  
R. N. WENSLEY
Keyword(s):  
Fusarium Oxysporum ◽  
Leaf Area ◽  
Fusarium Wilt ◽  
Growth Rates ◽  
Growth Trends ◽  
Thiophanate Methyl ◽  
Systemic Fungicides ◽  
Total Growth

Three systemic fungicides, benomyl (Benlate 50 WP), thiophanate-methyl (Cercobin 70 WP), and thiophanate (Cercobin 50 WP), used as soil drenches, snowed growth-regulating properties in wilt-susceptible and resistant muskmelon grown in soil infested with Fusarium oxysporum f. sp. melonis (Leach and Currence) Snyd. and Hans.). After an initial 12 days of suppression, growth rates accelerated, and enhanced total growth (leaf area) was obtained for most cultivars. Although similarities of growth trends were found, cultivars reacted differently when the three systemic compounds were applied to steam-sterilized compost.

scholarly journals Penetration and post-infection development of root-knot nematodes in watermelon

2018 ◽  
Vol 15 (4) ◽  
pp. e1010 ◽  
Author(s):  
Manuel López-Gómez ◽  
Soledad Verdejo-Lucas
Keyword(s):  
Life Cycle ◽  
Post Infection ◽  
Egg Laying ◽  
Initial Population ◽  
Post Inoculation ◽  
Second Stage ◽  
Progress Curve ◽  
Third Stage ◽  
Reproduction Factor ◽  
Nematode Development

Meloidogyne javanica has showed less reproductive success than M. incognita in watermelon genotypes. This study was conducted to elucidate the low reproduction of M. javanica in watermelon. The post-infection development of M. javanica in watermelon ‘Sugar Baby’ was determined at progressively higher initial population (Pi) levels at two time points during the life cycle. Plants were inoculated with 0, 25, 50, 100, 200, and 300 second-stage juveniles (J2)/plant. The increase in Pi was correlated with the penetration rates (R2= 0.603, p<0.001) and total numbers of nematodes in the root (R2 =0.963, p< 0.001) but there was no correlation between the Pi and the reproduction factor (eggs/plant/Pi). The population in the roots at 26 days post-inoculation (dpi) consisted primarily of third-stage juveniles (J3) with a small presence of J2 and fourth stages, and egg-laying females. The dominance of the J3, when egg-laying females are expected, point to the malfunction of the feeding sites that failed to support nematode development beyond the J3 stage. The similarities in egg-laying females at 26 and 60 dpi imply the disruption of the life cycle. Watermelon compensated for M. javanica parasitism by increasing vine length (19% to 33%) and dry top weight (40%) in comparison with the non-inoculated plants. The area under the vine length progress curve was significantly larger as the Pi progressively increased (R²=0.417, p<0.001). Physiological variation was detected between the M. incognita populations. M. arenaria had less ability to invade watermelon roots than did M. incognita and M. javanica.

scholarly journals Size Matters: Biological and Food Safety Relevance of Leaf Damage for Colonization of Escherichia coli O157:H7 gfp+

2021 ◽  
Vol 11 ◽  
Author(s):  
Emina Mulaosmanovic ◽  
Sofia T. Windstam ◽  
Ivar Vågsholm ◽  
Beatrix W. Alsanius
Keyword(s):  
Food Safety ◽  
Leaf Area ◽  
Plant Tissue ◽  
Spinacia Oleracea ◽  
Leafy Vegetables ◽  
Leaf Damage ◽  
Post Inoculation ◽  
Depth Of Invasion ◽  
Damage Level ◽  
E Coli

This study examined the biological and food safety relevance of leaf lesions for potential invasion of food pathogens into the plant tissue (internalization). This was done by determining the role of artificial leaf damage in terms of damaged leaf area on proliferation of E. coli O157:H7 gfp+. In a two-factorial experiment, unwashed fresh baby leaf spinach (Spinacia oleracea L.) was subjected to four damage levels (undamaged, low, moderate, high damage; factor 1) and three incubation intervals (0, 1, 2 days post-inoculation; factor 2). Individual leaves were immersed for 15 s in a suspension loaded with E. coli O157:H7 gfp+ (106 CFU × mL–1). The leaves were analyzed individually using image analysis tools to quantify leaf area and number and size of lesions, and using confocal laser scanning and scanning electron microscopy to visualize leaf lesions and presence of the introduced E. coli strain on and within the leaf tissue. Prevalence of E. coli O157:H7 gfp+ was assessed using a culture-dependent technique. The results showed that size of individual lesions and damaged leaf area affected depth of invasion into plant tissue, dispersal to adjacent areas, and number of culturable E. coli O157:H7 gfp+ directly after inoculation. Differences in numbers of the inoculant retrieved from leaf macerate evened out from 2 days post-inoculation, indicating rapid proliferation during the first day post-inoculation. Leaf weight was a crucial factor, as lighter spinach leaves (most likely younger leaves) were more prone to harbor E. coli O157:H7 gfp+, irrespective of damage level. At the high inoculum density used, the risk of consumers’ infection was almost 100%, irrespective of incubation duration or damage level. Even macroscopically intact leaves showed a high risk for infection. These results suggest that the risk to consumers is correlated with how early in the food chain the leaves are contaminated, and the degree of leaf damage. These findings should be taken into account in different steps of leafy green processing. Further attention should be paid to the fate of viable, but non-culturable, shiga-toxigenic E. coli on and in ready-to-eat leafy vegetables.

scholarly journals Prebloom Treatments to Alleviate Cold Injury in Apple

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 807E-807
Author(s):  
E.W. Stover ◽  
T.E. Paine ◽  
W.C. Stiles
Keyword(s):  
Leaf Area ◽  
Untreated Control ◽  
Fruit Set ◽  
Fruit Size ◽  
Cold Injury ◽  
Seed Number ◽  
Flower Buds ◽  
Active Growth ◽  
Strong Trend ◽  
Winter Temperatures

Damage to xylem subtending apple buds is often observed following very low winter temperatures. Reports suggest that prebloom application of boron, zinc, and urea facilitate recovery. Prebloom nutrient treatments were applied to `McIntosh' and `Empire' at three sites in Spring 1994. The following treatments were applied to drip at half-inch green: boron (22.8 mM, solubor); Zn-EDTA (0.75 mM); boron and Zn-EDTA; boron, Zn-EDTA, and urea (59.4 mM). Another treatment used boron and Zn-EDTA at half-inch green, followed by boron, Zn-EDTA, and urea at pink. Spur leaf area, fruit set, fruit size, and seed number were determined. There were no clear treatment effects at the warmest site (mid-winter low –32C); however, this orchard was more variable than other treatment sites. The intermediate site (mid-winter low –37C) had a strong trend of increasing fruit set in `Empire' and `McIntosh' as more nutrients were applied. The combined half-inch green and pink treatment significantly increased fruit set by 23.8% compared to the untreated control. At the coldest site (mid-winter low –42C), `Empire' again displayed a strong trend of increasing fruit set with additional nutrients. All treatments combining boron and zinc significantly increased fruit set. The combined half-inch green and pink treatment increased fruit set by 43%. At this site `McIntosh' did not respond to treatment. However, `McIntosh' trees had continued active growth into late Fall 1993 and sustained severe cold injury in November. Data suggest that, when they were effective, nutrient treatments resulted in increased retention of flower buds on damaged spurs.

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