scholarly journals Effects of Phosphonate and Mefenoxam Treatments on Development of Perennial Cankers Caused by Two Phytophthora spp. on Almond

Plant Disease ◽  
2005 ◽  
Vol 89 (3) ◽  
pp. 241-249 ◽  
Author(s):  
G. T. Browne ◽  
M. A. Viveros
Keyword(s):  
Topical Treatment ◽  
Prunus Dulcis ◽  
San Joaquin Valley ◽  
Disease Suppression ◽  
Phytophthora Cactorum ◽  
Time Intervals ◽  
Chemical Treatments ◽  
Foliar Sprays ◽  
Phytophthora Spp

Orchard experiments were conducted to evaluate chemical treatments for management of perennial cankers caused by Phytophthora cactorum and P. citricola on almond (Prunus dulcis) in the San Joaquin Valley of California. Single preventive foliar sprays with phosphonate were tested by wounding and inoculating tree trunks and branches with either pathogen at time intervals from 15 days to 5 months after spraying. One to 3 months after inoculation, resulting cankers were measured. Preventive foliar sprays with phosphonate in the fall or spring suppressed development of cankers for up to 5 months after treatment; mean canker lengths on the trees sprayed with phosphonate before inoculation were 22 to 98% smaller than those on trees that received no phosphonate. In subsequent tests, preventive chemigation with phosphonate in spring or summer also inhibited canker expansion. A curative topical treatment with either fosetyl-Al or mefenoxam on cankers caused by P. cactorum or P. citricola reduced canker expansion by 36 to 88%. Neither preventive nor therapeutic treatments eradicated the pathogens from the diseased tissues, but disease ratings made 1 year after the treatments indicated extended disease suppression. Phosphonate and mefenoxam treatments can effectively manage almond scion cankers caused by P. cactorum or P. citricola.

Timing of Aldicarb Applications to Control Meloidogyne arenaria in Peanut1

2001 ◽  
Vol 28 (2) ◽  
pp. 73-75 ◽  
Author(s):  
J. R. Rich ◽  
D. W. Gorbet
Keyword(s):  
Arachis Hypogaea ◽  
Chemical Treatment ◽  
Optimal Time ◽  
Meloidogyne Arenaria ◽  
Root Knot Nematode ◽  
Population Densities ◽  
Time Intervals ◽  
Yield Increase ◽  
Post Harvest ◽  
Chemical Treatments

Abstract Four fieldtrialswere conductedin northwest Florida to determine the efficacyofaldicarb appliedat varyingtime intervals after planting on peanut (Arachis hypogaea) to manage the peanut root-knot nematode, Meloidogyne arenaria. Initial treatments with aldicarb (Temik 15G), fenamiphos (Nemacur 15G), and phorate (Thimet 15G) were made at planting of peanut cv. Southern Runner. The chemicals were applied as 20-cm-wide bands over the open seed furrow using a tractor-mounted Gandy applicator. Post-plant treatments were made with a Gandy applicator at time intervals from 28 to 104 dafter planting as 36-cm-wide bands over the row centers. Post-harvest M. arenaria population densities were affected little by any chemical treatment compared to the control. The efficacy of the chemical treatments was variable and averaged onlya 295-kglha yield increase for the single at-plant applications of aldicarb compared to the control. Allat-plant + post-plant aldicarb treatments increased yield over the control by an average of712 kg¡ ha. Results from these trials did not establish a single optimal time for post-plant application of aldicarb on peanut. Data from these tests, however, indicated that a post-plant aldicarb treatment can be applied latter than previously recommended in Florida.

scholarly journals Relationship Between the Application of Foliar Chemicals to Reduce Common Scab Disease of Potato and Correlation with Thaxtomin A Toxicity

Plant Disease ◽  
2012 ◽  
Vol 96 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Robert S. Tegg ◽  
Ross Corkrey ◽  
Calum R. Wilson
Keyword(s):  
Measurement Error ◽  
Common Scab ◽  
Russet Burbank Potato ◽  
Disease Suppression ◽  
Tuber Initiation ◽  
Strongly Correlated ◽  
Symptom Development ◽  
Thaxtomin A ◽  
Foliar Sprays ◽  
Streptomyces Spp

Production of the phytotoxin thaxtomin A by pathogenic Streptomyces spp. is essential for induction of common scab disease in potato. The disease can be significantly reduced by a range of chemicals applied as foliar sprays before tuber initiation. We tested a range of chemicals that had previously demonstrated varying capacities to reduce common scab for both disease suppression and their ability to inhibit thaxtomin A toxicity in both ‘Desiree’ and ‘Russet Burbank’ potato. Our results for disease suppression generally supported previous studies. Our tuber slice assays with thaxtomin A showed a strong correlation between the ability of the chemical to suppress common scab symptom development and the ability of the chemical to inhibit thaxtomin A toxicity. A Bayesian measurement error linear regression model was derived for each cultivar and trial and demonstrated a clear positive relationship between disease and thaxtomin-A-induced necrosis. The relationships obtained were much stronger than would have been obtained without adjustment for measurement error. This demonstrates that disease mitigation using chemical foliar sprays is strongly correlated with the ability of the chemical to inhibit thaxtomin A toxicity, suggesting this mechanism as a key mode of action for understanding this novel disease control strategy.

scholarly journals Genetic and Pathogenic Variation in Phytophthora cactorum Affecting Fruit and Nut Crops in California

Plant Disease ◽  
2006 ◽  
Vol 90 (2) ◽  
pp. 161-169 ◽  
Author(s):  
R. G. Bhat ◽  
P. M. Colowit ◽  
T. H. Tai ◽  
M. K. Aradhya ◽  
G. T. Browne
Keyword(s):  
Genomic Dna ◽  
Significant Proportion ◽  
Aflp Analysis ◽  
Phytophthora Cactorum ◽  
Aflp Data ◽  
Minor Variation ◽  
Phytophthora Spp ◽  
Pathogenic Variation ◽  
Plant Nursery ◽  
Management Approaches

Isolates of Phytophthora cactorum and 15 other species of Phytophthora were characterized according to their genomic DNA, pathogenicity, and sensitivity to mefenoxam. Amplified fragment length polymorphism (AFLP) analysis was completed for 132 isolates of P. cactorum (30 from almond, 86 from strawberry, 5 from walnut, and 11 from other hosts) and 22 isolates of 15 other Phytophthora spp. from various hosts. All 16 Phytophthora spp. were distinguishable by unique AFLP banding patterns. Cluster analysis of the AFLP data revealed high coefficients of genetic similarity (>0.9) among all California isolates of P. cactorum. Analysis of molecular variance indicated that, among all 132 isolates of P. cactorum, 30.8 and 24.5% of the AFLP variation was associated with hosts and geographical sources of isolates, respectively, whereas 15.0% of the variation was associated with isolate niche (i.e., an aerial plant part, portion of the root system, or soil). Among the 86 isolates of P. cactorum from strawberry, characterization by source in the production system (i.e., fruiting field or plant nursery) did not account for a significant proportion of the variation (0.6%, P = 0.204). In pathogenicity tests on strawberry plants (cv. Diamante) in a greenhouse, isolates of P. cactorum from hosts other than strawberry and an isolate from a strawberry fruit caused only negligible amounts of disease, but isolates from strawberry root systems were highly aggressive. On excised shoot segments of almond (cv. Drake), all isolates of P. cactorum originally from almond were pathogenic, and 8 of 17 isolates of the pathogen from other hosts caused significantly less disease than the almond isolates. All 132 isolates of P. cactorum were sensitive to mefenoxam at 1 ppm. Populations of P. cactorum in California apparently are mefenoxam sensitive and exhibit host specificity with relatively minor variation in genomic DNA. The genetic variation observed in P. cactorum included significant geographical and host origin components, which has implications for disease management approaches.

scholarly journals Baseline Sensitivities of New Fungicides and Their Toxicity to Selected Life Stages of Phytophthora Species from Citrus in California

Plant Disease ◽  
2018 ◽  
Vol 102 (4) ◽  
pp. 734-742 ◽  
Author(s):  
Morgan A. Gray ◽  
Wei Hao ◽  
Helga Förster ◽  
James E. Adaskaveg
Keyword(s):  
Phytophthora Species ◽  
Effective Concentration ◽  
Life Stages ◽  
Phytophthora Citrophthora ◽  
Mean Values ◽  
Chemical Treatments ◽  
Phytophthora Spp ◽  
Chlamydospore Formation ◽  
Oospore Formation

Phytophthora citrophthora, P. syringae, P. nicotianae, and P. hibernalis are important pathogens of citrus in California but few chemical treatments are currently available. In vitro toxicities of four new fungicides to isolates of Phytophthora spp. from California were determined. Mean effective concentration values to inhibit mycelial growth by 50% for ethaboxam, fluopicolide, mandipropamid, oxathiapiprolin, and mefenoxam were 0.068, 0.04, 0.004, 0.0003, and 0.039 µg/ml, respectively, for 62 isolates of P. citrophthora; 0.005, 0.045, 0.003, 0.0001, and 0.008 µg/ml, respectively, for 71 isolates of P. syringae; 0.016, 0.057, 0.005, 0.0005, and 0.183 µg/ml, respectively, for 31 isolates of P. nicotianae; and 0.030, 0.018, 0.005, <0.0003, and ≤0.001 µg/ml, respectively, for two isolates of P. hibernalis. Mean values for ≥90% inhibition of sporangia formation of four isolates of P. citrophthora were 0.1, 0.28, 0.026, 0.005, and 55 µg/ml for ethaboxam, fluopicolide, mandipropamid, oxathiapiprolin, and mefenoxam, respectively. Zoospore cyst germination of P. citrophthora was most inhibited by oxathiapiprolin and mandipropamid. Chlamydospore formation of P. nicotianae was most sensitive to oxathiapiprolin, with a mean ≥90% reduction (EC>90) of 0.002 µg/ml, moderately sensitive to mandipropamid (EC>90 = 0.2 µg/ml) and mefenoxam (EC>90 = 0.6 µg/ml), and least sensitive to ethaboxam and fluopicolide (EC>90 = 1 µg/ml). Oospore formation of P. nicotianae was inhibited by ≥90% using oxathiapiprolin at 0.0004 µg/ml, mandipropamid at 0.02 µg/ml, ethaboxam at 0.1 µg/ml, or fluopicolide at 0.4 µg/ml, whereas 62% inhibition was obtained by mefenoxam at 40 µg/ml.

scholarly journals (329) Postharvest Urea Foliar Sprays Affect Almond and Prune Leaf Nitrogen and Sulfur Dynamics

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1065E-1066
Author(s):  
Franz J. A. Niederholzer ◽  
R. Scott Johnson
Keyword(s):  
Crop Production ◽  
Temporal Dynamics ◽  
Dry Weight ◽  
Prunus Dulcis ◽  
Leaf Nitrogen ◽  
Foliar Sprays ◽  
Tree Crop ◽  
Environmentally Sound ◽  
Foliar Urea ◽  
Leaf N

Urea foliar sprays may be a more efficient and environmentally sound alternative to soil applied fertilizer N in the postharvest period in tree crop production in California. While tree crop sulfur (S) status can interact with tree N status to affect growth, we know of no study assessing tree crop leaf N and S dynamics following fall (postharvest) foliar urea applications. We conducted a field study to measure temporal dynamics of leaf N and leaf S (% dry weight basis) following postharvest urea sprays on prune (Prunusdomestica) and almond (Prunus dulcis). June-budded nursery stock prune (`French' on Myro 29C) and almond (`Price' on Lovell) trees were sprayed to dripping with 6.5% (w/w) and 10% (w/w) standard urea solutions, respectively. Prunes were sprayed on 1 Oct. 2003 and almonds on 18 Nov. 2003. Leaf samples were taken over a 3-week (almond) or 8-week (prune) period, beginning just before treatment. Foliar urea sprays significantly increased prune (23%) and almond (14%) leaf N compared to untreated control within 8 days of application. This affect was transient, as there were no differences in leaf N concentrations between treated and untreated trees at final leaf sampling. Urea sprays did not affect almond leaf S concentration relative to untreated trees. Prune leaf S was significantly reduced compared to untreated trees 8 days after treatment, but only on that sampling date. Remobilization of S from the leaves of control trees of either species was not apparent.

scholarly journals Natural Ingredients Common in the Trás-os-Montes Region (Portugal) for Use in the Cosmetic Industry: A Review about Chemical Composition and Antigenotoxic Properties

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5255
Author(s):  
Sara Gonçalves ◽  
Isabel Gaivão
Keyword(s):  
Chemical Composition ◽  
Topical Treatment ◽  
Ecological Impact ◽  
Prunus Dulcis ◽  
Sambucus Nigra ◽  
Skin Rejuvenation ◽  
Cosmetic Industry ◽  
Aging Properties ◽  
Organic Farmers ◽  
Agricultural Diversity

The natural cosmetics market has grown since consumers became aware of the concept of natural-based ingredients. A significant number of cosmetics have an ecological impact on the environment and carry noxious and chemically potent substances. Thus, the use of natural and organic cosmetics becomes increasingly important since it is clear that topical treatment with cosmeceuticals can help improve skin rejuvenation. A substantial investigation into the benefits that fruits and plants can bring to health is required. Studies have shown that antigenotoxic properties are linked to anti-aging properties. Several studies have shown potential antigenotoxicity in natural ingredients such as Almonds (Prunus dulcis), Elderberry (Sambucus nigra), Olives (Olea europaea), and Grapes (Vitis vinifera). This review presents an overview of research conducted on these natural ingredients, the most common in the Northeast of Portugal. This region of Portugal possesses the most organic farmers, and ingredients are easily obtained. The Northeast of Portugal also has climatic, topographic, and pedological differences that contribute to agricultural diversity.

Detection and Characterization of QoI-Resistant Phytophthora cactorum and P. nicotianae Causing Leather Rot in Florida Strawberry

Plant Disease ◽  
2021 ◽  
Author(s):  
Marcus Vinicius Marin ◽  
Teresa E Seijo ◽  
Ellias Zuchelli ◽  
Natalia A. Peres
Keyword(s):  
Point Mutations ◽  
Crown Rot ◽  
Cytb Gene ◽  
Phytophthora Cactorum ◽  
Phytophthora Spp ◽  
Mitochondrial Cytochrome B ◽  
Qualitative Resistance ◽  
Selection Of ◽  
Qoi Resistance

Phytophthora cactorum and P. nicotianae cause leather rot (LR) of fruit and Phytophthora crown rot (PhCR) in strawberry. LR occurs sporadically but can cause up to 70% fruit loss when weather is conducive. In Florida's annual strawberry winter production system, PhCR can be severe, resulting in plant stunting, mortality, and severe yield loss. Currently, azoxystrobin is labeled for control of LR but not for PhCR. The aims of this research were i) to determine the sensitivity of P. cactorum and P. nicotianae isolates from strawberry to azoxystrobin and ii) to investigate mechanisms of QoI-resistance present in P. cactorum and P. nicotianae based on the known point mutations within the cytb gene. Isolates of both Phytophthora spp. causing LR and PhCR were collected from multiple strawberry fields in Florida between 1997 and 2020. Isolates were tested for sensitivity to azoxystrobin at 0, 0.01, 0.1, 1.0, 10, and 50 µg/ml on potato dextrose agar (PDA) amended with SHAM (100 µg/ml). Isolates were separated into two groups, sensitive isolates, with the 50% effective concentration (EC50) values lower than 1.0 µg/ml, and resistant isolates having EC50 values higher than 50 µg/ml. P. cactorum and P. nicotianae resistance to azoxystrobin was found for isolates collected after 2010. The first 450 nucleotides of the mitochondrial cytochrome b (cytb) gene were sequenced from a selection of resistant and sensitive isolates of both species. The G143A mutation reported to confer resistance to azoxystrobin was found in all resistant P. cactorum isolates. However, in P. nicotianae, qualitative resistance was observed, but the isolates lacked all the known mutations in the cytb gene. This is the first report of resistance to azoxystrobin in P. cactorum and P. nicotianae.

scholarly journals Efficacy of Metalaxyl, Fosetyl-Aluminum, and Straw Mulch for Control of Strawberry Leather Rot Caused by Phytophthora cactorum

Plant Disease ◽  
1998 ◽  
Vol 82 (3) ◽  
pp. 329-332 ◽  
Author(s):  
M. A. Ellis ◽  
W. F. Wilcox ◽  
L. V. Madden
Keyword(s):  
Fruit Set ◽  
Early Growth ◽  
Early Spring ◽  
Disease Development ◽  
Phytophthora Cactorum ◽  
Fungicide Treatment ◽  
Straw Mulch ◽  
Foliar Sprays ◽  
Overhead Irrigation ◽  
Significant Difference

Chemical and cultural controls for strawberry leather rot, caused by Phytophthora cactorum, were compared in replicated plots on a commercial farm near Wooster, Ohio. Straw mulch, applied uniformly for winter protection, was removed in early spring from between the rows of all check and fungicide treatment plots. Supplemental straw mulch was applied to other plots to achieve a level of approximately 9 t/ha. Overhead irrigation, which caused the soil to puddle, was provided on alternate days during rain-free periods to promote disease development (58, 66, and 73% incidence in check plots for 1993, 1994, and 1995, respectively). Foliar sprays of fosetyl-Al, applied weekly from bloom through preharvest at rates (a.i.) of 2.24 and 4.48 kg/ha, provided 88 to 96% control, with no significant difference between fungicide rates. Metalaxyl (1.17 kg/ha), applied either once or twice as a soil drench from early growth through fruit set, provided 82 to 94% control. Straw mulch alone provided 95 to 99% control. Thus, straw mulch between the rows was equally or more effective than fungicides for controlling leather rot.

PHYTOPHTHORA SPP. IN SOILS OF THE OKANAGAN AND SIMILKAMEEN VALLEYS OF BRITISH COLUMBIA

1964 ◽  
Vol 42 (10) ◽  
pp. 1411-1415 ◽  
Author(s):  
D. L. McIntosh
Keyword(s):  
British Columbia ◽  
Irrigation Water ◽  
Soil Samples ◽  
Phytophthora Cactorum ◽  
Phytophthora Spp ◽  
Orchard Soils ◽  
Chemotactic Effect ◽  
Irrigated Soils ◽  
Cultivated Soils

Phytophthora cactorum is widely distributed in irrigated soils in the Okanagan and Similkameen valleys of British Columbia. Other species isolated, when over 1800 soil samples were assayed for the presence of Phytophthora fungi, were P. cryptogea twice, P. cambivora once, P. megasperma var. sojae once, and P. drechsleri twice. Phytophthora spp. were not recovered from virgin soils nor from non-irrigated cultivated soils, nor from orchard soils receiving irrigation water that is chlorinated. P. cactorum, P. cryptogea, and P. cambivora are pathogenic to rootlets of pear, cherry, apricot, and peach seedlings. P. megasperma var. sojae and P. drechsleri were weakly to non-pathogenic to these hosts. Pear and apple rootlets exerted a chemotactic effect on zoospores of P. cambivora and P. cactorum.

scholarly journals Population Structure of Xylella fastidiosa Associated with Almond Leaf Scorch Disease in the San Joaquin Valley of California

2015 ◽  
Vol 105 (6) ◽  
pp. 825-832 ◽  
Author(s):  
Hong Lin ◽  
Md Sajedul Islam ◽  
Juan C. Cabrera-La Rosa ◽  
Edwin L. Civerolo ◽  
Russell L. Groves
Keyword(s):  
Population Structure ◽  
Driving Forces ◽  
Xylella Fastidiosa ◽  
Prunus Dulcis ◽  
San Joaquin Valley ◽  
Leaf Scorch ◽  
Ssr Analysis ◽  
Cultivar Selection ◽  
Genetic Clusters ◽  
Almond Leaf Scorch

Xylella fastidiosa causes disease in many commercial crops, including almond leaf scorch (ALS) disease in susceptible almond (Prunus dulcis). In this study, genetic diversity and population structure of X. fastidiosa associated with ALS disease were evaluated. Isolates obtained from two almond orchards in Fresno and Kern County in the San Joaquin Valley of California were analyzed for two successive years. Multilocus simple-sequence repeat (SSR) analysis revealed two major genetic clusters that were associated with two host cultivars, ‘Sonora’ and ‘Nonpareil’, respectively, regardless of the year of study or location of the orchard. These relationships suggest that host cultivar selection and adaptation are major driving forces shaping ALS X. fastidiosa population structure in the San Joaquin Valley. This finding will provide insight into understanding pathogen adaptation and host selection in the context of ALS disease dynamics.

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