Incidence Of Rhizoctonia Root Rot Research Articles

Effect of limestone dose on the incidence of Rhizoctonia root rot and soybean yield in four soil types

AbstractRhizoctonia root rot (RRR) is a disease caused by the soilborne pathogen Rhizoctonia solani, which kills soybean plants in patches over croplands. Control is difficult because the pathogen survives in the soil and has a wide host range; therefore, cultural control methods might help to diminish disease pressure. The objective of this study was to evaluate liming as a strategy to reduce the incidence of RRR in soybean grown in four soil types: acrisol (Ac), cambisol Ta (CaTa), cambisol Tb (CaTb) and nitisol (Nit). The treatments were arranged in a factorial design of four doses of limestone (0, 3, 6 and 9 t/ha) at two sites within each field (inside and outside a Rhizoctonia patch). The incidence of RRR inside the patch was on average 40.3% whereas outside it was 1.2%. The reduction in disease incidence was 3.9%, 3.7%, 3.6% and 1.8% per 1000 kg of limestone applied for the Ac, CaTa, CaTb and Nit soils, respectively. The highest soybean yield was of 4713 and 3349 kg/ha for the Ac and Nit soils with application of 6.6 and 6.2 t/ha of limestone, respectively. Soybean yield in the cambisols increased linearly with liming, with an increase in yield of 121 and 172 kg/ha in CaTa and CaTb, respectively, for each 1000 kg of limestone applied. Thus, liming reduced the incidence of RRR in all soils and promoted better soybean nutrition, increasing soybean yield. Therefore, liming is a practice that contributes to both soil fertility and disease control.

Hyperspectral imaging of symptoms induced by Rhizoctonia solani in sugar beet: comparison of input data and different machine learning algorithms

The fungal pathogen Rhizoctonia solani is one of the most important soil-borne diseases in sugar beet production worldwide. Root and crown rot caused by this fungus are traditionally recognized later in the cropping season by rating the above-ground symptoms like wilting and chlorosis on foliage, and dark brown lesions at the base of petioles. The present study was designed to evaluate noninvasive sensors and machine learning for measuring disease incidence and early detection. Eight-weeks-old plants were inoculated with the pathogen in two different concentrations and under controlled conditions. Hyperspectral images in the visible and near-infrared range from leaf were obtained in time-series. One hundred thirty and fifteen spectral features were selected in two levels by using the recursive feature elimination method (RFE) and a clustering approach. Subsequently, five types of machine-learning methods were employed to train four types of spectral data containing reflectance values, vegetation indices, selected variables of the RFE process and selected variables of an RFE-clustering process. The best classifier was obtained from a partial least squares modeling process and required a number of 15 spectral features, which include first and second derivatives of the wavelength spectrum as well as the Ctr3, EVI and PSSRa vegetation index. This investigation proves that under controlled conditions early detection of indirect symptoms caused by Rhizoctonia root rot in sugar-beet plants is possible. Scoring of disease incidence of Rhizoctonia root rot at 10 dai was 3 to 5 times higher with a machine-learning classifier in comparison with the human visual rating.

Antifungal potential and defense gene induction in maize against Rhizoctonia root rot by seed extract of Ammi visnaga (L.) Lam.

Methanol extracts from five medicinal plants ( Eucalyptus tereticornis Sm., Ammi visnaga (L.) Lam., Azadirachta indica A. Juss., Rheum Palmatum L., and Adansonia digitata L.) were assessed in vitro for antifungal activity against Rhizoctonia solani Kuhn, the causal agent of Rhizoctonia root rot of maize. All tested extracts showed antifungal activity with varied extents. Ammi visnaga (khella) extract showed the greatest activity compared with the untreated experimental controls. Observations using transmission electron microscopy showed ultrastructural changes in hyphal cells as a response to exposure to khella extract. Gas chromatography-mass spectrometric analysis of khella extract showed the presence of 69 compounds. The antifungal properties of the extracts were mainly attributed to their content of coumarins and fatty acids. In the greenhouse experiment, treatment of maize plants with khella extract at 15% gave the least incidence of Rhizoctonia root rot. Results of DD-PCR showed up- and down- regulations of some genes in maize as response to the treatment with khela extract. Identification of the randomly selected genes from DD-PCR revealed that they were defense-related, as S-domain class receptor-like kinase 3 and glutathione-S-transferase1. Real-time PCR showed induction in the gene expression of the pathogenesis-related protein chitinases (2.36 fold) and thaumatin-like proteins (8.99 fold) by treatment with khella extract at 15%, which was greater expression than detected at 10 and 20%. This indicates triggering effects from the extract on the maize immune system against the R. solani infection in a concentration-dependent manner. The efficient, low-cost and eco-friendly characteristics of khella extract indicate that it could be used for the control of Rhizoctonia root rot of maize.

Efficacy of Some Plant Extracts Against Rhizoctonia Solani on Pea

Efficacy of Some Plant Extracts AgainstRhizoctonia Solanion PeaAntifungal activity of ethanol-water extracts of four medicinal plants, cinnamon (Cinnamomum verumPresl.), anise (Pimpinella anisumL.), black seed (Nigella sativaL.) and clove (Syzygium aromaticumL. Merr. & Perry.) was investigated against pea (Pisum sativumL.) root-rot fungusRhizoctonia solani. In vitroantifungal activity test shown a high growth inhibition at concentration (4%) of each plant extract. The highest antifungal activity was recorded for clove extract which causes complete growth inhibition at concentration of 1%. Efficacy of clove extract on disease incidence ofRhizoctoniaroot-rot of pea was investigated in the greenhouse pot experiment. Clove extract at concentration 4% as well as the chemical fungicide recorded highly significant increase in the percentage of survived plants (40 and 48%, respectively) and highly significant decrease in disease incidence.

Root Diseases of Wheat and Barley During the Transition from Conventional Tillage to Direct Seeding.

The use of direct seeding (no-till) in place of tillage can reduce soil erosion and improve water infiltration. However, despite these improvements in soil quality, growers in the Pacific Northwest are reluctant to adopt direct seeding, partially because of fears of increased root diseases caused by Gaeumannomyces graminis var. tritici, Rhizoctonia spp., and Pythium spp. To examine the effect of the transition from conventional tillage to direct seeding, field plots were established at two locations. One site had been managed with direct seeding for 12 years, and the second had been conventionally tilled. Over 4 years, a portion of each plot was tilled or direct seeded, and planted to wheat or barley. Plants in the tilled plots had consistently more crown roots than plants in direct-seeded plots. Rhizoctonia root rot and yield did not differ between tillage types during the first 2 years of the study. However, in the third and fourth years of the transition to direct seeding, a higher incidence of Rhizoctonia root rot, increased hyphal activity of R. solani, and reduced yields were observed in direct-seeded plots. Populations of R. oryzae and Pythium spp., and incidence of take-all were the same for both management practices.

Brassica napus seed meal soil amendment modifies microbial community structure, nitric oxide production and incidence of Rhizoctonia root rot

A low glucosinolate content (21.8 μmol g −1) Brassica napus seed meal (RSM) applied to orchard soils altered communities of both pathogenic and saprophytic soil micro-organisms. RSM amendment reduced infection by native and introduced isolates of Rhizoctonia spp. and recovery of Pratylenchus spp. from apple roots. Root infection by Rhizoctonia solani AG-5 was also suppressed in split-root assays where a portion of the root system was cultivated in RSM-amended soils and the remainder grown in the presence of the pathogen but lacking RSM. R. solani hyphal growth was not inhibited by RSM amendment. Suppression of Pratylenchus was attained to an equivalent extent by amending soils with either RSM or soybean meal (SM) when applied to provide a similar N content. Thus, glucosinolate hydrolysis products did not appear to have a significant role in the suppression of Rhizoctonia spp. or Pratylenchus spp. obtained via RSM amendment. RSM amendment elevated populations of Pythium spp. and of ammonia-oxidizing bacteria that release nitric oxide but suppressed fluorescent pseudomonad numbers. Streptomyces spp. soil populations increased significantly in response to RSM but not SM amendment. The vast majority of Streptomyces spp. recovered from the apple rhizosphere produced nitric oxide and possessed a nitric oxide synthase homolog. We propose that transformations in the bacterial community structure are associated with the observed control of Rhizoctonia root rot, with NO production by soil bacteria potentially having a role in the induction of plant systemic resistance.

Effect of sowing point design and tillage practice on the incidence of Rhizoctonia root rot, take-all and cereal cyst nematode in wheat and barley

Effect of tillage treatments on the cereal root diseases, rhizoctonia root rot, take-all and cereal cyst nematode, and on grain yield of cereals were tested in 4 field experiments over 3 years. Conventionally cultivated treatments were compared with a range of direct-drill treatments using either a standard tined seed drill equipped with 10 cm sowing points, a specialised drill designed to give minimal soil disturbance or a standard tined seed drill equipped with a range of commercial or modified narrow points designed to provide soil disturbance from 0 to 5.0 cm below seed depth. Direct-drilled treatments that disturbed the soil below seed depth (DDD) and treatments that included 1 cultivation prior to sowing (CPS) resulted in a reduction of rhizoctonia root rot when compared with direct-drilled treatments that did not disturb the soil below seed depth (DDN). When seasonal conditions encouraged volunteer plant growth before sowing, a chemical fallow treatment applied 3 weeks before sowing significantly reduced rhizoctonia root rot in all direct-drilled plots. This was a significant factor in DDD treatments providing effective control of rhizoctonia root rot. Take-all was present in 3 of the 4 experiments. In 2 experiments, take-all was significantly higher in plots following DDN treatments than DDD or CPS treatments and in 1 experiment there was no effect of tillage. Cereal cyst nematode was present in 1 of the 4 experiments. The level of root damage from cereal cyst nematode was least in plots following DDN treatments, higher following DDD treatments and highest following CPS treatments. The influence of tillage practice on grain yield was closely related to the effect of tillage on cereal root disease when levels of disease were moderate to high. Where the incidence of root disease was low, grain yield differences due to tillage treatments were generally related to agronomic factors such as seed depth and seedbed condition.

Influence of preseason weed management and in-crop treatments on two successive wheat crops. 2. Take-all severity and incidence of Rhizoctonia root rot

The effects of cultivation and herbicide use to control weeds in wheat on wheat growth, the severity of take-all, and the incidence of rhizoctonia root rot were studied for 2 seasons. Preseason treatments were no weed control, paraquat (0.20 kg a.i./ha), glyphosate (0.18 kg a.i./ha or 4 applications of 0.72 kg a.i./ha), and heavy grazing. In-crop treatments were cultivation plus trifluralin, direct drilling plus chlorsulfuron, and direct drilling alone. At the site, take-all was the main disease while rhizoctonia root rot was relatively minor. Glyphosate applied 4 times at 0.72 kg a.i./ha over the previous spring and summer led to greater wheat dry matter (DM) production, significantly (P<0.05) less severe take-all, and a lower incidence of rhizoctonia root rot in the first year than the other preseason treatments. Spraytopping with glyphosate (0.18 kg a.i./ha) or paraquat (0.20 kg a.i./ha) and heavy grazing reduced take-all severity but not the incidence of rhizoctonia root rot. Conventional cultivation resulted in more wheat DM, significantly less severe take-all, and a lower incidence of rhizoctonia root rot than direct drilling. Grain yields reflected the trends of the DM production despite severe yield loss due to head frosting. Plots were split for cultivation and direct drilling in the second year. The highest wheat DM and grain yields were in the cultivated treatments but the effects of cultivation on take-all did not carry over from the first year. In both years, take-all was most severe in the control treatment and least severe in the treatment with the high rate of glyphosate (P<0.05). In the second wheat crop, however, take-all severity was similar in the 2 glyphosate, paraquat, and grazed treatments. The effect of a weed-free fallow obtained by use of a high rate of glyphosate was nullified in the second wheat crop because of a high carryover of volunteer wheat seedlings during the intervening wet summer. There was also a greater incidence of rhizoctonia root rot in the control than in the other treatments, and cultivation again reduced disease incidence compared with direct drilling.

Changes in take-all (Gaeumannomyces graminis var. tritici), Rhizoctonia root rot (Rhizoctonia solani) and soil pH in continuous wheat with annual applications of nitrogenous fertiliser in Western Australia

Experiments were conducted to test the hypotheses that: (i) continuous cropping with wheat would lead to a decline in take-all, (ii) ammonium nitrogen would reduce take-all compared with nitrate nitrogen, and (iii) that both sources of nitrogen would lead to a decline in soil pH. Attempts were also made to confirm that rhizoctonia root rot would vary unpredictably in continuous wheat and would be reduced by nitrogen. Wheat was grown without nitrogen (Nil) or with sodium nitrate (SN) or ammonium sulfate (AS) for 11, 10 and 9 consecutive years at Newdegate, Esperance and Mount Barker respectively. Rates of nitrogen were 50, 25 and 45 kg ha-1 at Newdegate, Esperance and Mount Barker respectively. A decline in take-all incidence was established at Newdegate, and plots treated with AS generally had a lower take-all incidence than did plots without nitrogen or treated with SN. At Esperance, a decline in take-all incidence was established only in AS treated plots. Take-all incidence was lower in plots treated with AS than plots without nitrogen or treated with SN in 6 years out of 10 at Esperance. No take-all decline was observed at Mount Barker and take-all incidence was rarely lower in plots treated with AS than in those without nitrogen or treated with SN. All treatments reduced soil pH at Newdegate and Esperance, which were weakly buffered sites, but at Mount Barker (a highly buffered site) only AS reduced pH. Rhizoctonia root rot was not found at Mount Barker. At Newdegate and Esperance it first occurred in the eighth and fifth crops respectively. Incidence peaked at about 60% of plants being affected in the ninth crop at Newdegate and 95% in year 7 at Esperance, and then declined to less than 5% at both sites. Applications of nitrogen had no effect on incidence of rhizoctonia root rot. Yields varied considerably between sites and years. Combining results for all years at each site showed that AS increased yield at all sites and SN increased yields at Newdegate and Mount Barker compared with no nitrogen. The continued use of AS at Mount Barker eventually had an adverse effect on yield.

Effect of Pesticides and Nitrogen Fertility on Rhizoctonia Root Rot of Sugarbeet

The presence and incidence of root and crown rot of sugarbeet (Beta vulgaris L.), caused by the soil-borne fungus Rhizoctonia so­ lani Kuhn, has been reported in the United States by numerous authors, first by Pammel (5)3 in 1891 and most recently by Hecker and Ruppel (3) in 1977. An increasing incidence of the disease was noted by Hecker and Ruppel (3) without attributing a cause, but shorter crop rotations were implicated. Crop rotation currently is the only means of control. Chemical treatments of soil, seed, or plants are not sufficiently effective or are not commercially feasible, and resistant commercial varieties are not yet available. Potential effects of contemporary pesticide treatments on rhi­ zoctonia root rot in field-grown sugarbeet have not been reported. However, Altman and Campbell (1) and Tisserat et al. (7) have re­ ported increased rhizoctonia damping off of sugarbeet seedlings in greenhouse and growth chamber experiments where the soils were amended with cyc10ate and aldicarb. The effect of nitrogen fertility on sugarbeet root rot has been tested only to a limited extent. Hills and Axtell (4) in 1950 reported a lower incidence of rhizoctonia root rot on nitrogen fertilized plots than on non-fertilized plots. Schuster and Harris (6) in 1960 reported similar results on plots of continuous beets and in a 2-year rotation, but not in 3, 4, or 6 year rotations. The purpose of this paper is to report the effects of commonly used pesticides and of nitrogen fertility treatments on rhizoctonia root rot of sugarbeet.