scholarly journals Temporal Dynamics of Phytophthora Blight on Bell Pepper in Relation to the Mechanisms of Dispersal of Primary Inoculum of Phytophthora capsici in Soil

2000 ◽  
Vol 90 (2) ◽  
pp. 148-156 ◽  
Author(s):  
L. S. Sujkowski ◽  
G. R. Parra ◽  
M. L. Gumpertz ◽  
J. B. Ristaino
Keyword(s):  
Root Growth ◽  
Temporal Dynamics ◽  
Phytophthora Capsici ◽  
Disease Onset ◽  
Soil Surface ◽  
Growth Chamber ◽  
Phytophthora Blight ◽  
Primary Inoculum ◽  
Growth Chamber Studies ◽  
Root Spread

The effect of components of primary inoculum dispersal in soil on the temporal dynamics of Phytophthora blight epidemics in bell pepper was evaluated in field and growth-chamber experiments. Phytophthora capsici may potentially be dispersed by one of several mechanisms in the soil, including inoculum movement to roots, root growth to inoculum, and root-to-root spread. Individual components of primary inoculum dispersal were manipulated in field plots by introducing (i) sporangia and mycelia directly in soil so that all three mechanisms of dispersal were possible, (ii) a plant with sporulating lesions on the soil surface in a plastic polyvinyl chloride (PVC) tube so inoculum movement to roots was possible, (iii) a wax-encased peat pot containing sporangia and mycelia in soil so root growth to inoculum was possible, (iv) a wax-encased peat pot containing infected roots in soil so root-to-root spread was possible, (v) noninfested V8 vermiculite media into soil directly as a control, or (vi) wax-encased noninfested soil as a control. In 1995 and 1996, final incidence of disease was highest in plots where sporangia and mycelia were buried directly in soil and all mechanisms of dispersal were operative (60 and 32%) and where infected plants were placed in PVC tubes on the soil surface and inoculum movement to roots occurred with rainfall (89 and 23%). Disease onset was delayed in 1995 and 1996, and final incidence was lower in plants in plots where wax-encased sporangia (6 and 22%) or wax-encased infected roots (22%) were buried in soil and root growth to inoculum or root-to-root spread occurred. Incidence of root infections was higher over time in plots where inoculum moved to roots or all mechanisms of dispersal were possible. In growth-chamber studies, ultimately all plants became diseased regardless of the dispersal mechanism of primary inoculum, but disease onset was delayed when plant roots had to grow through a wax layer to inoculum or infected roots in tension funnels that contained small volumes of soil. Our data from both field and growth-chamber studies demonstrate that the mechanism of dispersal of the primary inoculum in soil can have large effects on the temporal dynamics of disease.

Factors Involved in Alachlor Injury to the Potato (Solanum tuberosum)

Weed Science ◽  
1977 ◽  
Vol 25 (6) ◽  
pp. 482-486 ◽  
Author(s):  
J.N. Belote ◽  
T.J. Monaco
Keyword(s):  
Solanum Tuberosum ◽  
Soil Surface ◽  
Growth Chamber ◽  
Herbicide Application ◽  
Time Of Application ◽  
Plant Emergence ◽  
Chamber Studies ◽  
Growth Chamber Studies

Results from greenhouse and growth chamber studies indicated that alachlor [2-chloro-2′,6-diethyl-N-(methoxymethyl) acetanilide] injury to ‘Superior’ potatoes (Solanum tuberosumL.) was related to time of herbicide application and temperature. Injury to the ‘Superior’ cultivar was observed when alachlor was applied just before potato emergence. Necrosis of shoots near the soil surface, shoot dieback, stem swelling, leaf crinkle, and plant stunting were characteristic symptoms of alachlor injury. Cool temperatures appeared to intensify the injury. ‘Superior’ potatoes outgrew injury within 41 days after treatment. Herbicide placement studies in the growth chamber suggested that alachlor or its metabolites were absorbed by the shoots of emerging ‘Superior’ potatoes. Under growth chamber conditions the ‘Katahdin’ cultivar was injured by preemergence applications of alachlor when the herbicide was applied just before plant emergence. Injury symptoms were similar to those observed on the ‘Superior’ cultivar. ‘Pungo’ and ‘Norchip’ potatoes were tolerant to preemergence applications of the herbicide regardless of time of application.

Eucalyptus tree influence on spatial and temporal dynamics of fine-root growth in an integrated crop-livestock-forestry system in southeastern Brazil

Rhizosphere ◽  
2021 ◽  
pp. 100415
Author(s):  
Wanderlei Bieluczyk ◽  
Marisa de Cássia Piccolo ◽  
Marcos Gervasio Pereira ◽  
George Rodrigues Lambais ◽  
Moacir Tuzzin de Moraes ◽  
...  
Keyword(s):  
Root Growth ◽  
Fine Root ◽  
Temporal Dynamics ◽  
Southeastern Brazil ◽  
Spatial And Temporal Dynamics ◽  
Fine Root Growth

scholarly journals Stable Isotope Biogeochemistry of Seabird Guano Fertilization: Results from Growth Chamber Studies with Maize (Zea Mays)

PLoS ONE ◽  
2012 ◽  
Vol 7 (3) ◽  
pp. e33741 ◽  
Author(s):  
Paul Szpak ◽  
Fred J. Longstaffe ◽  
Jean-François Millaire ◽  
Christine D. White
Keyword(s):  
Zea Mays ◽  
Stable Isotope ◽  
Growth Chamber ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Seabird Guano

scholarly journals Fitness of Isolates of Phytophthora capsici Resistant to Mefenoxam from Squash and Pepper Fields in North Carolina

Plant Disease ◽  
2008 ◽  
Vol 92 (10) ◽  
pp. 1439-1443 ◽  
Author(s):  
Adalberto C. Café-Filho ◽  
Jean Beagle Ristaino
Keyword(s):  
North Carolina ◽  
Phytophthora Capsici ◽  
Colony Growth ◽  
Relative Fitness ◽  
In Planta ◽  
Phytophthora Blight ◽  
In Vivo Experiments ◽  
First Time

Despite the wide adoption of mefenoxam (Ridomil Gold EC) for vegetables in North Carolina, the incidence of Phytophthora blight on pepper (Capsicum annuum) and squash (Cucurbita pepo) is high. Seventy-five isolates of Phytophthora capsici were collected in five pepper and one squash field in order to assess mefenoxam sensitivity. The relative fitness of resistant and sensitive isolates was contrasted in vitro by their respective rates of colony growth and their ability to produce sporangia in unamended V8 juice agar medium. In in vivo experiments, the aggressiveness of isolates on pepper was evaluated. The frequency of resistant isolates in North Carolina populations was 63%, considerably higher than resistance levels in areas where mefenoxam is not widely adopted. Resistant isolates grew on amended media at rates >80 to 90% and >100% of the nonamended control at 100 μg ml-1 and 5 μg ml-1, respectively. Sensitive isolates did not growth at 5 or 100 μg ml-1. All isolates from three fields, including two pepper and a squash field, were resistant to mefenoxam. Populations from other fields were composed of either mixes of sensitive and resistant isolates or only sensitive isolates. Response to mefenoxam remained stable during the course of in vitro and in planta experiments. Occurrence of a mefenoxam-resistant population of P. capsici on squash is reported here for the first time in North Carolina. When measured by rate of colony growth, sporulation in vitro, or aggressiveness in planta, fitness of resistant isolates was not reduced. Mefenoxam-resistant isolates from squash were as aggressive on pepper as sensitive or resistant pepper isolates. These results suggest that mefenoxam-resistant populations of P. capsici are as virulent and fit as sensitive populations.

Control of Kochia in Sugarbeets With Benzadox

Weed Science ◽  
1970 ◽  
Vol 18 (1) ◽  
pp. 183-185 ◽  
Author(s):  
D. M. Weatherspoon ◽  
E. E. Schweizer
Keyword(s):  
Acetic Acid ◽  
Beta Vulgaris ◽  
Temperature Regime ◽  
Environmental Conditions ◽  
Growth Chamber ◽  
Kochia Scoparia ◽  
Simulated Rain ◽  
Chamber Studies ◽  
Growth Chamber Studies

Benzadox [(benzamidooxy)acetic acid] applied at 1, 2, 3, and 4 lb/A as a postemergence treatment controlled kochia [Kochia scoparia(L.) Schrad.] selectively in sugarbeets (Beta vulgarisL.). Control increased as the rate of benzadox increased, but some kochia survived at the 4-lb/A rate. Competition from these plants reduced the yields of sugarbeet roots and sucrose. Where surviving kochia plants were removed by hand 7 weeks after emergence, all sugarbeets treated with benzadox yielded as well as the hand-weeded checks. In growth chamber studies, the activity of benzadox was increased by temperature and decreased by simulated rain which occurred within 4 hr following application. Under a temperature regime of 70 F day and 40 F night, if simulated rain was delayed for 8 hr, the control of kochia was identical to that obtained where no simulated rain followed treatment. The growth chamber studies confirmed our results with the performance of benzadox under different environmental conditions in the field.

Dicamba Volatility

Weed Science ◽  
1979 ◽  
Vol 27 (5) ◽  
pp. 486-493 ◽  
Author(s):  
Richard Behrens ◽  
W. E. Lueschen
Keyword(s):  
Field Experiments ◽  
Volatile Component ◽  
Growth Chamber ◽  
Gas Chromatography Mass Spectrometry ◽  
Terminal Bud ◽  
Anisic Acid ◽  
Blotter Paper ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Soybean Leaves

Factors influencing dicamba drift, especially vapor drift, were examined in field and growth chamber studies. In field experiments, potted soybeans[Glycine max(L.) Merr.]. exposed to vapors arising from corn (Zea maysL.) foliarly treated with the sodium (Na), dimethylamine (DMA), diethanolamine (DEOA), orN-tallow-N,N1,N1-trimethyl-1,3-diaminopropane (TA) salts of dicamba (3,6-dichloro-o-anisic acid), developed dicamba injury symptoms. Dicamba volatilization from treated corn was detected with soybeans for 3 days after the application. Dicamba vapors caused symptoms on soybeans placed up to 60m downwind of the treated corn. When vapor and/or spray drift caused soybean terminal bud kill, yields were reduced. In growth chamber studies, dicamba volatility effects on soybeans could be reduced by lowering the temperature or increasing the relative humidity. Rainfall of 1mm or more on treated corn ended dicamba volatilization. The dicamba volatilization was greater from corn and soybean leaves than from velvetleaf (Abutilon theophrastiMedic.) leaves and blotter paper. The volatilization of dicamba formulations varied in growth chamber comparisons with the acid being most volatile and the inorganic salts being the least volatile. However, under field conditions, use of less volatile formulations did not eliminate dicamba symptoms on soybeans. The volatile component of the commercial DMA salt of dicamba was identified by gas chromatography-mass spectrometry as free dicamba acid.

Foliar and Root Absorption of Atrazine Applied Postemergence to Giant Foxtail

Weed Science ◽  
1969 ◽  
Vol 17 (2) ◽  
pp. 251-256 ◽  
Author(s):  
Lafayette Thompson ◽  
F. W. Slife
Keyword(s):  
Field Experiments ◽  
Soil Surface ◽  
Dry Weight ◽  
Field Studies ◽  
Simulated Rainfall ◽  
Root Absorption ◽  
Giant Foxtail ◽  
Setaria Faberii ◽  
Chamber Studies ◽  
Growth Chamber Studies

In growth chamber studies, high relative humidity and rewetting crystalline spray deposits of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) increased absorption by and phytotoxicity to giant foxtail (Setaria faberii Herrm.), but phytotoxicity was restricted to expanded (unrolled) leaves unless some atrazine was absorbed by the roots. Though phytotoxicity was increased by simulated rainfall when root absorption was prevented, an appreciable number of the plants were killed only when atrazine residues were washed into the soil. In field studies, atrazine applied to a wet soil surface was as effective as the same rate of atrazine foliarly applied. In other field experiments, atrazine applied to giant foxtail on a wet soil and followed by simulated rainfall reduced stand and dry weight, but on a dry soil and not followed by simulated rainfall, atrazine reduced dry weight less and did not reduce stand. These results are due to root absorption of atrazine from wet soil. Spray additives increased phytotoxicity.

Variation in Growth Habit and Response to Chemicals among Three Common Cocklebur (Xanthium strumarium) Selections

Weed Science ◽  
1982 ◽  
Vol 30 (4) ◽  
pp. 339-343 ◽  
Author(s):  
Robert N. Andersen
Keyword(s):  
Growth Habit ◽  
Main Stem ◽  
Growth Chamber ◽  
Xanthium Strumarium ◽  
Leaf Necrosis ◽  
Chamber Studies ◽  
Growth Chamber Studies

Burs of common cocklebur (Xanthium strumarium L.) obtained from Stoneville, Mississippi; Urbana, Illinois; and Lamberton, Minnesota, were used in greenhouse and growth chamber studies. The Mississippi and the Illinois strains were both classified as being in the “strumarium” complex of X. strumarium, whereas, the Minnesota strain was classified as being in the “hybrid” complex. The Minnesota common cocklebur developed branch leaves in the leaf axils of the main stem to a much greater extent than did the Mississippi and Illinois common cocklebur. The Mississippi common cocklebur was frequently more tolerant of postemergence applications of bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] than were the Illinois and Minnesota common cockebur. The Mississippi and Illinois common cocklebur developed leaf necrosis when sprayed with an insecticide formulation containing malathion (o, o-dimethyl phosphorodithioate of mercaptosuccinate) and petroleum solvents; the Minnesota common cocklebur did not.

Germination and Emergence of Burcucumber (Sicyos angulatus)

Weed Science ◽  
1981 ◽  
Vol 29 (1) ◽  
pp. 83-86 ◽  
Author(s):  
R. K. Mann ◽  
C. E. Rieck ◽  
W. W. Witt
Keyword(s):  
Zea Mays ◽  
Glycine Max ◽  
Water Absorption ◽  
Osmotic Potential ◽  
Moisture Stress ◽  
Growth Chamber ◽  
Cold Stratification ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Osmotic Potentials

Mechanical scarification of burcucumber (Sicyos angulatusL.) seeds resulted in increased water absorption and germination. Burcucumber germination occurred at temperatures ranging from 15 to 35 C with optimum germination occurring from 20 to 30 C. Scarified burcucumber seeds were more sensitive to simulated moisture stress than were either soybean [Glycine max(L.) Merr. ‘Williams’] or corn [Zea maysL. ‘Pioneer Brand 3369A’]. Regardless of osmotic potential, intact burcucumber seeds did not germinate; scarified seeds germinated at osmotic potentials to −6 bars. Cold stratification at 4 C for 18 weeks modified seedcoat permeability so that 11% of non-scarified burcucumber seeds germinated. Increasing depth of planting decreased emergence with limited emergence occurring at depths of 15 and 16 cm in field and growth chamber studies, respectively.

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