scholarly journals Suppression of Phytophthora Root Rot in Red Raspberries with Cultural Practices and Soil Amendments

HortScience ◽  
2005 ◽  
Vol 40 (6) ◽  
pp. 1790-1795 ◽  
Author(s):  
Kevin Maloney ◽  
Marvin Pritts ◽  
Wayne Wilcox ◽  
Mary Jo Kelly
Keyword(s):  
Root Rot ◽  
Cultural Practices ◽  
Soil Amendments ◽  
Severe Disease ◽  
Phosphorous Acid ◽  
Growth And Yield ◽  
Phytophthora Root Rot ◽  
Disease Symptoms ◽  
Phytophthora Fragariae ◽  
Infested Site

Various soil amendments and cultural practices were examined in both a phytophthora-infested (Phytophthora fragariae var. rubi) (+PFR) and uninfested field (–PFR) planted to `Heritage' red raspberries. Although plants in the +PFR field did not exhibit typical disease symptoms due to unseasonably dry weather, their growth was less than those in the –PFR field. After 2 years, plants in the +PFR site had the highest yields in plots treated with phosphorous acid or amended with gypsum, whereas compost-amended plots had the lowest yields in both +PFR and –PFR sites. A second field study confirmed the positive effect of gypsum on growth and yield of raspberries in an infested site. In a third study, `Titan' raspberries grown under greenhouse conditions in pots containing unamended soil from the infested site, then flooded, exhibited severe disease symptoms; however, pasteurization of the soil, treatment with phosphorous acid and metalaxyl fungicide, or gypsum amendment mostly prevented symptoms from developing. These three studies suggest that a preplant soil amendment containing certain readily available forms of calcium, such as found in gypsum, can help suppress phytophthora root rot and increase survival, growth and yield of raspberries in sites where the pathogen is present.

scholarly journals Preplant Soil Amendments influence the Incidence of Phytophthora Root Rot in `Heritage' Red Raspberry

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 468E-469
Author(s):  
K.E. Maloney ◽  
M.P. Pritts ◽  
W.F. Wilcox ◽  
M.E. Sorrells
Keyword(s):  
Disease Control ◽  
Root Rot ◽  
Soil Amendments ◽  
Phosphorous Acid ◽  
Integrated Approach ◽  
Future Research ◽  
Causal Organism ◽  
Disease Symptoms ◽  
Foliar Disease ◽  
Infested Site

Phytophthora is a severe root rot disease in most raspberry production regions throughout the world. Disease control options are limited to raised bed culture and fungicide applications. Few Phytophthora-resistant varieties are available that have commercial quality. Little is known about how soil amendments (i.e., composts, fertilizers, and limestones) influence Phytophthora control in raspberry. We evaluated the effects of preplant soil modification on the incidence of Phytophthora root rot in red raspberries. The experiment was conducted simultaneously at two sites to differentiate between the nutritional value of the amendments and the disease control value. One site has a known history of Phytophthora and a the second site is assumed to be free of the causal organism. Raspberry plant growth and fruit yield measurements were taken for all treatments. Preplant soil application of Gypsum (CaSo4) and post-plant applications of phosphorous acid sprays (H3PO3) had the greatest fruit yields compared to all other treatments in the Phytophthora-infested site. Gypsum-treated plots had greater cane diameter, cane height, and cane density compared to the control plots on the Phytophthorainfested site. A second experiment was conducted to further investigate the use of gypsum for control of Phytophthora in raspberries. Field soil was collected for use as potting medium from each of the aforementioned sites and pathogen free `Titan' plants were established in the greenhouse. After subsequent floodings, gypsum-treated soils delayed foliar disease symptoms compared to the control plots. At the end of the experiment, the control plants had 100% foliar disease symptoms and gypsum-treated pots had 33% disease symptoms. This study suggests that gypsum could be used in an integrated approach to Phytophthora management in raspberries. Future research should identify minimal effective rates of gypsum, examine other calcium sources, and determine effectiveness in other fruit crops.

scholarly journals Variation in Disease Severity Caused by Phytophthora cinnamomi, P. plurivora, and Pythium cryptoirregulare on Two Rhododendron Cultivars

Plant Disease ◽  
2018 ◽  
Vol 102 (12) ◽  
pp. 2560-2570 ◽  
Author(s):  
Jerry E. Weiland ◽  
Carolyn F. Scagel ◽  
Niklaus J. Grünwald ◽  
E. Anne Davis ◽  
Bryan R. Beck ◽  
...  
Keyword(s):  
Disease Control ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Severe Disease ◽  
Phytophthora Species ◽  
Relative Resistance ◽  
Inoculum Level ◽  
Phytophthora Root Rot ◽  
Mild Disease ◽  
Comparative Information

Rhododendrons are an important crop in the ornamental nursery industry, but are prone to Phytophthora root rot. Phytophthora root rot is a continuing issue on rhododendrons despite decades of research. Several Phytophthora species are known to cause root rot, but most research has focused on P. cinnamomi, and comparative information on pathogenicity is limited for other commonly encountered oomycetes, including Phytophthora plurivora and Pythium cryptoirregulare. In this study, three isolates each of P. cinnamomi, P. plurivora, and Py. cryptoirregulare were used to inoculate rhododendron cultivars Cunningham’s White and Yaku Princess at two different inoculum levels. All three species caused disease, especially at the higher inoculum level. P. cinnamomi and P. plurivora were the most aggressive pathogens, causing severe root rot, whereas Py. cryptoirregulare was a weak pathogen that only caused mild disease. Within each pathogen species, isolate had no influence on disease. Both P. cinnamomi and P. plurivora caused more severe disease on Cunningham’s White than on Yaku Princess, suggesting that the relative resistance and susceptibility among rhododendron cultivars might be similar for both pathogens. Reisolation of P. cinnamomi and P. plurivora was also greater from plants exhibiting aboveground symptoms of wilting and plant death and belowground symptoms of root rot than from those without symptoms. Results show that both P. cinnamomi and P. plurivora, but not Py. cryptoirregulare, are important pathogens causing severe root rot in rhododendron. This study establishes the risks for disease resulting from low and high levels of inoculum for each pathogen. Further research is needed to evaluate longer term risks associated with low inoculum levels on rhododendron health and to explore whether differences among pathogen species affect disease control.

scholarly journals Raised Beds and Metalaxyl for Controlling Phytophthora Root Rot of Raspberry

HortScience ◽  
1993 ◽  
Vol 28 (11) ◽  
pp. 1106-1108 ◽  
Author(s):  
K.E. Maloney ◽  
W.F. Wilcox ◽  
J.C. Sanford
Keyword(s):  
Root Rot ◽  
Disease Incidence ◽  
Silt Loam ◽  
Red Raspberry ◽  
Highly Pathogenic ◽  
Phytophthora Root Rot ◽  
Respective Treatment ◽  
Phytophthora Fragariae ◽  
Raised Bed ◽  
Substantial Control

`Titan' red raspberry (Rubis idaeus L.), highly susceptible to root rot caused by Phytophthora fragariae Hickman var. rubi Wilcox & Duncan (syns. P. erythroseptica Pethyb., “highly pathogenic” P. megasperma Drechs.), was planted in June 1990 in a silt loam naturally infested with the pathogen. Raked beds (0.36 m high) dramatically reduced disease incidence and severity relative to flatbed treatments. In contrast, metalaxyl at 372 mg·m-1 of row provided little benefit when applied to flat beds and provided consistently moderate but statistically insignificant effects when applied to raised beds. Relative to the flat bed system, primocane vigor was increased in 1992 by 16%, 190%, and 224% in the flat bed plus metalaxyl, raised bed, and raised bed plus metalaxyl treatments, respectively; total yields were increased by 7%, 231%, and 272% with these same respective treatment. The results indicate that raised-bed planting systems can provide substantial control of phytophthora root rot of red raspberries even when highly susceptible varieties are grown on otherwise marginal sites. Metalaxyl appears more effective as a supplement rather than substitute for raised beds under such conditions. Chemical name used: N- (2,6-dimethylphenyl) -N- (methoxyacetyl)alanine methyl ester (metalaxyl).

scholarly journals Performance and Resistance to Phytophthora Crown and Root Rot in Squash Lines

2020 ◽  
Vol 30 (5) ◽  
pp. 608-618 ◽  
Author(s):  
Kyle E. LaPlant ◽  
Gregory Vogel ◽  
Ella Reeves ◽  
Christine D. Smart ◽  
Michael Mazourek
Keyword(s):  
Root Rot ◽  
Cucurbita Pepo ◽  
Field Experiments ◽  
Phytophthora Capsici ◽  
Severe Disease ◽  
Field Trials ◽  
Disease Symptoms ◽  
Resistant Lines ◽  
Oomycete Pathogen ◽  
Crown And Root Rot

Phytophthora crown and root rot, caused by the oomycete pathogen Phytophthora capsici, is a devastating disease of squash and pumpkin (Cucurbita pepo). No currently available cultivars provide complete resistance to this disease. Three newly developed squash lines and four hybrids were evaluated in greenhouse and field experiments for their resistance to phytophthora crown and root rot as well as for their horticultural performance. The three newly developed lines ranked among the most resistant entries included in 2 years of field trials. In addition, in a separate greenhouse experiment, one of the lines was shown to display the least severe disease symptoms among a group of accessions previously reported to possess partial resistance to phytophthora crown and root. Furthermore, the resistance was observed to be robust to several isolates of P. capsici. However, the phytophthora-resistant lines had reduced yield relative to standard squash cultivars. These lines are useful for continued breeding efforts toward a phytophthora crown and root rot-resistant cultivar.

scholarly journals Phytophthora Root Rot of Blueberry Increases with Frequency of Flooding

HortScience ◽  
1999 ◽  
Vol 34 (4) ◽  
pp. 693-695 ◽  
Author(s):  
Amal de Silva ◽  
Keith Patterson ◽  
Craig Rothrock ◽  
Ron McNew
Keyword(s):  
Disease Severity ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Disease Incidence ◽  
Severe Disease ◽  
Vaccinium Corymbosum ◽  
Root Infection ◽  
Phytophthora Root Rot ◽  
Severity Rating ◽  
Linear Relationships

Phytophthora root rot is a severe disease on blueberry (Vaccinium corymbosum L.) in poorly drained soils. Little is known about how mulching and frequent waterlogging affect disease severity in blueberries. Phytophthora cinnamomi Rands was grown on rice hulls, which were incorporated into the soil at the rate of 10% (v:v). Waterlogging conditions were imposed for 48 hours 1 week after planting on mulched and nonmulched blueberry plants at weekly, biweekly, and monthly intervals for a total of 3 months. Control plants were not subjected to flooding. The severity of Phytophthora root rot increased with time. Significant linear relationships were found between flooding interval and disease severity rating of shoot, percentage of root infection, and shoot and root dry weights of plants. Disease symptoms were minimal in control plants, but shoot disease rating and percentage of root infection were high in mulched and nonmulched plants that were flooded every week. Shoot and root dry weights were higher in 1997 than in 1996. In 1996, mulched plants had higher shoot dry weights than did nonmulched plants. Disease incidence was higher with weekly and biweekly flooding than with monthly or no flooding. However, mulching did not affect root infection.

scholarly journals Reaction of spring barley cultivars grown in Finland to soil-borne infection by Bipolaris sorokiniana and to its toxic metabolites

1985 ◽  
Vol 57 (2) ◽  
pp. 85-96
Author(s):  
Aarne Kurppa
Keyword(s):  
Root Rot ◽  
Spring Barley ◽  
Severe Disease ◽  
Bipolaris Sorokiniana ◽  
Toxin Production ◽  
Yield Losses ◽  
Disease Symptoms ◽  
Barley Cultivars ◽  
Toxic Metabolites ◽  
The Mean

Soil-borne infection of Bipolaris sorokiniana caused foot and root rot in all spring barley cultivars studied. Significant differences in susceptibility of the cultivars and pathogenicity of the fungus isolates were found. Primary symptoms caused by the fungus were seedling blight, later foot and root rot. Yield losses caused by the fungus varied from 3 % to 33 % the mean being c. 15 %. Yield losses could occur without severe disease symptoms. Toxic metabolites produced by the fungus induced visible foot and root symptoms in all cultivars tested and caused lesions in the leaves of some cultivars. Variability in toxin production of fungus isolates as well as the reaction of a cultivar to toxins was demonstrated. The cultivars most susceptible to soil-borne infection by the fungus also showed the most severe symptoms when exposed to toxic metabolites of the fungus.

Effects of Viruses (SPVD) on Growth and Yield of Sweet Potato

1979 ◽  
Vol 15 (3) ◽  
pp. 253-256 ◽  
Author(s):  
S. K. Hahn
Keyword(s):  
Sweet Potato ◽  
Ipomoea Batatas ◽  
Virus Disease ◽  
Severe Disease ◽  
Growth And Yield ◽  
Root Yield ◽  
Disease Symptoms ◽  
Vein Clearing ◽  
Chlorophyll Level ◽  
Yield Trials

SUMMARYSweet potato (Ipomoea batatas L.) virus disease (SPVD) causes severe disease symptoms of various combinations of leaf strapping, vein-clearing, puckering and stunting. The disease is widespread, especially in Africa, and yield is adversely affected, though there are no figures to quantify this effect nor is it known how yield is affected. Loss of tuberous root yield due to SPVD was studied in sweet potato showing symptoms of the disease. Slips were obtained from plants with and without symptoms and two yield trials in 2 years were conducted by planting them alternately in rows. Yield of fresh tubers was reduced by 78% in plants showing SPVD symptoms but the reduced chlorophyll level of diseased leaves did not appear to affect yield.

Comparison of phosetyl-Al, phosphorous acid and metalaxyl for the long-term control of Phytophthora root rot of avocado

1987 ◽  
Vol 27 (3) ◽  
pp. 471 ◽  
Author(s):  
KG Pegg ◽  
AW Whiley ◽  
PW Langdon ◽  
JB Saranah
Keyword(s):  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Phosphorous Acid ◽  
Growing Season ◽  
Phytophthora Root Rot ◽  
The Third ◽  
Consecutive Season

Avocado trees affected by root rot caused by Phytophthora cinnamomi Rands recovered rapidly when given injections into the trunk of phosetyl-A1 or phosphorous acid. Injected trees had greater yields(47.9-67.5 v. 4.3 kg fruit per tree) and lower leaf chloride levels (0.8-2.4 v. 4.2%, w/w) than controls in the third season after starting treatment. Phosphorous acid residues (21-83 mg kg-1) were detected in fruit from injected trees. Metalaxyl applied to the soil twice each growing season successfully controlled root rot for the first 2 seasons, but there was a significant resurgence of decline symptoms after the third consecutive season of use.

scholarly journals Integrated Control of Phytophthora Root Rot of Red Raspberry

Plant Disease ◽  
1999 ◽  
Vol 83 (12) ◽  
pp. 1149-1154 ◽  
Author(s):  
W. F. Wilcox ◽  
M. P. Pritts ◽  
M. J. Kelly
Keyword(s):  
Root Rot ◽  
Disease Incidence ◽  
Integrated Control ◽  
Plant Performance ◽  
Growth And Yield ◽  
Silty Clay ◽  
Variable Response ◽  
Poor Growth ◽  
Phytophthora Root Rot ◽  
Straw Mulch

Various components of an integrated program for controlling Phytophthora root rot of red raspberries were examined in a factorial experiment conducted for three growing seasons in a silty clay loam naturally infested with Phytophthora fragariae var. rubi. The factors were: (i) cultivar (highly susceptible Titan versus moderately resistant Newburgh); (ii) bed height (flat versus raised); (iii) straw mulch application (yes versus no); (iv) preplant treatment with the biological control fungus Trichoderma (=Gliocladium) virens (yes versus no); and (v) seasonal applications of the fungicide metalaxyl (yes versus no). Disease incidence was assessed visually, and severity was measured with respect to cane density, cane vigor, and yield. Cultivar was the most important factor, having a highly significant (P < 0.0001) main effect on nearly every measure of disease incidence and severity; it also interacted significantly with most other factors for at least some of these measures. In general, such interactions resulted from the positive response of Newburgh to treatments that had little effect on the consistently poor growth and yield of Titan, or from the variable response of Titan to treatments that had little effect on the consistently low visual disease ratings for Newburgh. Raised bed cultivation consistently reduced disease incidence and improved plant performance (particularly for Newburgh) and was the only factor other than cultivar that significantly improved yield, i.e., 5.6 versus 2.0 kg per Newburgh plot on raised versus flat beds, respectively. Although metalaxyl initially provided a substantial decrease in disease incidence on Titan, most of these plants eventually died. In contrast, metalaxyl provided modest yield benefits for Newburgh, and highest yields were obtained when metalaxyl was used in conjunction with raised beds, i.e., means of 2.2 versus 1.8 kg for the treated versus untreated plots on flat beds and 6.3 versus 5.1 kg, respectively, on raised beds. Straw mulch increased soil moisture levels and exacerbated disease incidence and severity. The biocontrol treatment had relatively little effect on disease, although there was some indication of marginally improved plant growth in treated plots.

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