Biological control of root and stem rot of greenhouse cucumber, caused by Fusarium oxysporum f. sp. radicis-cucumerinum, by lettuce soil amendment

2005 ◽  
Vol 24 (2) ◽  
pp. 135-140 ◽  
Author(s):  
G.C. Pavlou ◽  
D.J. Vakalounakis
2004 ◽  
Vol 14 (2) ◽  
pp. 240-242 ◽  
Author(s):  
Steve Rose ◽  
Zamir K. Punja

Eighteen cucumber (Cucumis sativus L.) cultivars (long English type) were screened for their susceptibility to fusarium root and stem rot caused by Fusarium oxysporum Schlechtend.: Fr. f.sp. radicis-cucumerinum D.J. Vakalounakis using seedlings at the third true-leaf stage. Roots were trimmed and dipped into a spore suspension (105 spores/mL) of the pathogen and the plants were re-potted. A disease severity index (DSI) was used to assess disease responses 4 or 8 weeks later based on plant mortality and the height of surviving plants compared to the noninoculated controls. `Sienna', `Amazing' and `Dominica' were most susceptible to infection and the resulting DSI values were significantly (P ≤ 0.05) higher compared to noninoculated control plants. The cultivars `Korinda', `Euphoria' and `Aviance' displayed significantly lower DSI values which were not significantly different from noninoculated control plants. The remaining 12 cultivars displayed DSI values which were intermediate between the above two classes of responses. The results from this study indicate there is the potential to identify and develop cultivars and breeding lines of greenhouse cucumbers with enhanced resistance to fusarium root and stem rot.


Plant Disease ◽  
2003 ◽  
Vol 87 (12) ◽  
pp. 1462-1470 ◽  
Author(s):  
S. Rose ◽  
M. Parker ◽  
Z. K. Punja

Potential disease control methods were evaluated against root and stem rot of cucumber (Cucumis sativus) caused by Fusarium oxysporum f. sp. radicis-cucumerinum. Crab/shrimp shell chitin; three composted media; the biological control agents Pseudomonas chlororaphis strain 63-28, Trichoderma harzianum (RootShield Drench), Streptomyces griseoviridis (Mycostop), Gliocladium catenulatum (Prestop WP, Prestop Mix), and Trichoderma (Gliocladium) virens (SoilGard); and the fungicides thiram or benomyl were added at seeding time followed by inoculation with the pathogen. The addition of chitin (4%, vol/vol) to a peat-based medium significantly (P ≤ 0.05) enhanced seedling growth, increased soil pH, and reduced F. oxysporum f. sp. radicis-cucumerinum populations, but the severity of disease was increased. The addition of composted media (greenhouse compost, windrow composted dairy solids, and vermi-composted dairy solids) to the seeding cavity in a rock wool block medium, followed 48 h later by inoculation with F. oxysporum f. sp. radicis-cucumerinum, reduced seedling mortality when measured after 37 days. Greenhouse compost was significantly (P ≤ 0.05) more suppressive than the other two composts, and the suppression was partially eliminated by sterilization of the compost. The biological control agent G. catenulatum (formulated as Prestop WP and Prestop Mix) significantly reduced seedling mortality when it was applied at seeding 24 h prior to inoculation with the pathogen in the rock wool block medium. None of the other biological control agents reduced disease incidence when compared with control plants under these experimental conditions. Pseudomonas chlororaphis and the fungicide thiram both significantly reduced plant mortality at 17 and 24°C when pathogen-infested seed was treated, or when bacteria-treated and fungicide-treated seed were planted into pathogen-infested peat medium at 24°C. Under semicommercial propagation conditions, treatments consisting of Prestop WP, RootShield Drench, My-costop, and windrow composted dairy solids reduced the severity of disease caused by F. oxysporum f. sp. radicis-cucumerinum in two out of three trials. The efficacy of the biological control agents was affected by seasonal differences in growing conditions, which affected the incidence and severity of the disease. The results from this study indicate that several different approaches can be used at seeding to control Fusarium root and stem rot on greenhouse cucumber.


2000 ◽  
Vol 46 (11) ◽  
pp. 1021-1028 ◽  
Author(s):  
T Kannangara ◽  
R S Utkhede ◽  
J W Paul ◽  
Z K Punja

Three composts were tested for their ability to suppress root and stem rot caused by the soil borne fungal pathogen Fusarium oxysporum f. sp. radicis-cucumerinum (FORC) on cucumber. Two of the composts were prepared from separated dairy solids either by windrow (WDS) or vermicomposting (VMC) while the third, obtained from International Bio-Recovery (IBR), was prepared from vegetable refuse using aerobic digestion. Three sets of potting mixes were prepared by mixing the composts with sawdust at varying ratios, and seeded with cucumber cv. Corona. After 14 days of growth in the greenhouse, inoculum of FORC (20 mL of 5 × 106micro-conidia per mL) was applied to each pot at three different times (14, 21, and 35 days). In unamended inoculated pots, the pathogen caused stunted growth and reduced flowers. Amendment of WDS in the potting mix suppressed these symptoms, while VMC and IBR had no effect. All three composts reduced the FORC colony forming units (cfu) at the end of the experiment (10 weeks). There was a large increase of fluorescent bacteria near the vicinity of roots particularly in WDS amended potting mixes. When water extracts of the composts were plated onto acidified potato dextrose agar (APDA), only IBR contained a potent thermostable inhibitor to FORC. This inhibitor was removed by activated charcoal but was not partitioned into petroleum ether at acid, basic, or neutral pH. Inhibition of FORC by IBR was not due to electrical conductivity or trace elements in the compost. Contrasting effectiveness of the WDS and VMC made from the same waste suggests that composting method can influence the disease suppression properties of the finished compost.Key words: Fusarium oxysporum f. sp. radicis-cucumerinum, biological control.


1987 ◽  
Vol 33 (5) ◽  
pp. 349-353 ◽  
Author(s):  
T. C. Paulitz ◽  
C. S. Park ◽  
R. Baker

Nonpathogenic isolates of Fusarium oxysporum were obtained from surface-disinfested, symptomless cucumber roots grown in two raw (nonautoclaved) soils. These isolates were screened for pathogenicity and biological control activity against Fusarium wilt of cucumber in raw soil infested with Fusarium oxysporum f. sp. cucumerinum (F.o.c.). The influence of three isolates effective in inducing suppressiveness and three ineffective isolates on disease incidence over time was tested. The effective isolates reduced the infection rate (R), based on linear regressions of data transformed to loge (1/1 – y). Effective isolate C5 was added to raw soil infested with various inoculum densities of F.o.c. In treatments without C5, the increase in inoculum densities of F.o.c. decreased the incubation period of wilt disease, but there was no significant difference in infection rate among the inoculum density treatments. Isolate C5 reduced the infection rate at all inoculum densities of F.o.c. Various inoculum densities of C5 were added to raw soils infested with 1000 cfu/g of F.o.c. In the first trial, infection rates were reduced only in the treatment with 10 000 cfu/g of C5; in the second trial, infection rates were reduced in treatments with 10 000 and 30 000 cfu/g of C5.


Plant Disease ◽  
2004 ◽  
Vol 88 (6) ◽  
pp. 645-649 ◽  
Author(s):  
D. J. Vakalounakis ◽  
Z. Wang ◽  
G. A. Fragkiadakis ◽  
G. N. Skaracis ◽  
D.-B. Li

Thirty-four isolates of Fusarium oxysporum, obtained in China from cucumber plants showing either Fusarium wilt (F. oxysporum f. sp. cucumerinum) or root and stem rot (F. oxysporum f. sp. radicis-cucumerinum) symptoms, were characterized by pathogenicity, vegetative compatibility, and random amplified polymorphic DNA (RAPD). Of these, 23 isolates were identified by pathogenicity as F. oxysporum f. sp. cucumerinum, and one as F. oxysporum f. sp. radicis-cucumerinum, while 10 isolates were avirulent on cucumber, melon, sponge gourd, and pumpkin. The Chinese isolates of F. oxysporum f. sp. cucumerinum were assigned to RAPD groups III and XXI and to vegetative compatibility group (VCG) 0183, four new VCGs, 0184 to 0187, and a single-member VCG included in the artificial VCG 018-. The Chinese isolate of F. oxysporum f. sp. radicis-cucumerinum was assigned to RAPD group I and bridging VCG 0260/0261. The occurrence of F. oxysporum f. sp. radicis-cucumerinum on cucumber is reported for the first time in China.


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