Yield and quality of Russet Burbank potato as influenced by interactions ofRhizoctonia,maleic hydrazide,and PCNB

Soil treatment with pentachloronitrobenzene (PCNB) at 22.4 kg/ha a.i. reduced symptoms of theRhizoctonia disease (Rhizoctonia solani Kühn) on potato (Solarium tuberosum L.) and resulted in significant increases in the numbers of stems and stolons. With disease control there was no effect on either total or U.S. #1 yield, but decreases of tuber size were evident and effects were observed on grade. Yield of malformed tubers was reduced by 35%, but this benefit was counteracted by a 41% increase of undersized tubers. Among U. S. 1’s, yield of non-size A’s (113 to 170 g) were increased by 22%, while tubers in optimum size ranges for french fries and bakers (> 284 g) were decreased by 24%. No effect was observed on carton sized tubers (170 to 369 g). Foliar sprays of maleic hydrazide (MH) applied on either of several dates (23 July, 2 Aug., 13 Aug.) at 3.4 kg/ha a.i. reduced total yield by 4.9 to 5.7%, but yields of U.S. #1 potatoes or sizes > 170 g were unaffected. Treatments with MH on either 23 July or 2 Aug. reduced yield of undersized potatoes by 23%. MH treatments did not interact with PCNB treatment to change either total yield or size, but adverse effects on U.S. #1 yields were indicated. MH treatments applied on either 2 Aug. or 13 Aug. reduced U.S. #1 yields among PCNB treated plots by 7 to 10%. MH reduced length/width ratios and, depending on date of application, increased specific gravity. PCNB did not influence tuber shape or specific gravity, but a significant reduction of standard deviations among length/width ratios indicated greater uniformity of shape with treatment.     

Comparison of two methods of PCNB application for control of Rhizoctonia infection of potatoes

A broadcast application of PCNB (Terraclor) resulted in a reasonably uniform distribution of the chemical in the soil with the concentration decreasing in a linear fashion with increasing depth in the soil profile. A banded application resuluted in a considerably higher chemical concentration at the 4–6 inch depth than at the 0–2 or the 2–4 inch depths. The problem of the lack of uniformity of chemical distribution could probably be solved by altering nozzle placement and size and allow use of the band method of application to minimize grower cost. More complete disking in the case of the broadcast treatment would probably result in a relatively uniform distribution of the chemical but at higher cost to the grower. PCNB application rates of 10, 15 and 25 lbs per acre broadcast and 71/2, 10 and 121/2 lbs per acre in a band significantly reduced the severity ofRhizoctonia infection of Russet Burbank potatoes but did not increase potato yields significantly.     

Evaluation ofLaetisaria arvalis as a biological control agent ofRhizoctonia solani on white potato

Laetisaria arvalis, a soil-inhabiting basidiomycete, reducedRhizoctonia solani infection of white potato. A greenhouse study that monitored population levels of both fungi showed that soil infested withL. arvalis suppressed the growth ofR. solani after eight wks. Populations ofL. arvalis andR. solani increased after 11 wks. when both fungi were infested simultaneously and whenL. arvalis was introduced to soil previously infested withR. solani. Five years of field studies showed that variousL. arvalis seed treatments and soil amendments reducedR. solani infection of stems and stolons and sclerotial formation on tubers equal to the standard chemical treatment of pentachloronitrobenzene (PCNB) + thiabendazole. No relationship was shown between populations ofL. arvalis andR. solani in field plot soils, but native or wild strains ofL. arvalis were shown to be present at detectable levels in field soils.     

Influences of the Rhizoctonia disease on production of the Russet Burbank potato

Pentachloronitrobenzene (PCNB) treatment (20 lb/A – 22.4 kg/ha) showed significant reduction ofRhizoctonia (Rhizoctonia solani Kühn) symptoms on potato. The PCNB treatment increased the number of non-girdled stolons as compared to untreated plots by 50, 34, and 30% at respective seedpiece spacings of 6, 9, and 12 in (15, 23, and 30 cm). Numbers of non-girdled stolons in PCNB-treated plots at 9- and 12-in spacing did not differ significantly from those in untreated plots at 6-in spacing. Yield differences (either total or U.S. #1) among treatments were not observed, but size differences were evident. Closer spacing or PCNB treatment or both increased the number of small U.S. #1 potatoes and decreased the number of large U.S. #1 potatoes (over 7 oz. - 199 g). Although the number of smaller potatoes was increased by 27% with PCNB treatment, the percentage of malformed tubers was reduced by 50%. Tuber size was reduced as the number of non-girdled stolons was increased (P =.001). Results suggestthat Rhizoctonia control may benefit the fresh potato packer and seedgrower by potentially reducing seed requirement/acre, by increasing capacity for single-drop seed production, and by greater control over U.S. #1 size.     

Dosage rates and application methods with PCNB for control of potato scab and rhizoctonia

American Journal of Potato Research - Pentachloronitrobenzene (PCNB) controlled potato scab in fine sandy loam of the Yakima Valley when applied at the rate of 50 pounds per acre broadcast before...     

Effect of fertilizer,fumigants, and fungicides on leafroll-net necrosis in Russet Burbank potatoes

A total of 112 combinations of 13 fumigants, fertilizers, and a fungicide was tested in replicated plots in eastern Washington in 1963 and 1964 to determine their effects on the net necrosis produced in Russet Burbank potatoes by the leafroll virus. Plots treated with Telone^® (dichloropropenes) or Telone+chloropicrin had significantly fewer tubers discolored with leafroll net necrosis than untreated plots; plots treated with lower rates of various chlorinated propenes and propanes or ethylene dibromide had fewer discolored tubers than plots treated with higher rates of these chemicals; and plots treated with higher rates of various combinations of dichloropropenes with methyl isothiocyanate or 3-bromo-1-propyne had fewer discolored tubers than plots treated with lower rates of these chemicals. An interaction took place between the chemicals and the leafroll virus that either increased or decreased the amount of net necrosis in the tubers. Other types of internal discoloration (OID) in the tubers were significantly increased by Telone treatments in some tests. Telone treatments showed no effects on OID in other tests compared to untreated tubers. Also, nitrogen, at 100 lb/acre and over, significantly increased the other types of discoloration over no nitrogen, but potassium at 0 to 150 lb/acre and pentachloronitrobenzene (PCNB) at 0 to 30 gal/acre showed no significant effect.     

Calcium and potassium fertilization of potatoes grown in North Florida. II. Effect on the bacterial soft rot potential in the tubers

In studies on a sandy soil in Florida over a 3-yr period (1984–86), applications of Ca (CaSO₄) inconsistently affected the bacterial soft rot potential of potato tubers (Solanum tuberosum). The potential was estimated from the severity of the disease (percent surface area decayed) in tubers that had been immersed in an aqueous cell suspension ofErwinia carotovora subsp.carotovora and then incubated 4 days in a mist chamber at 24 C. With freshly harvested tubers (tested within 5 days after harvest), disease severity averaged 49, 11, and 4% over all treatments in 1984, 1985, and 1986, respectively, which was roughly proportional to rainfall on the crop,e.g., 37, 18, and 15 cm, respectively. Disease severity decreased, did not change, and increased with increased Ca rate (0, 450, and 900 kg.ha^-1) in 1984, 1985, and 1986, respectively. In each season, severity was affected by interactions involving the Ca treatments. Most interactions involved cultivar. The efficacy of Ca applications to potatoes grown in low Ca soils for enhancement of tuber resistance to bacterial soft rot may be limited by factors associated with environment or cultivar that are not completely understood.     

Resistance of tubers from different potato cultivars to soft rot caused byErwinia carotovora subsp.atroseptica

Mechanically harvested tubers of 14 potato cultivars grown on both loamy sand and silt loam soils were evaluated for resistance to bacterial soft rot caused byErwinia carotovora subsp.atroseptica. Cultivars were also assayed for calcium and dry matter content to determine possible correlations with soft rot resistance. Resistance of potato tubers to bacterial soft rot was assayed after harvest by inoculating tubers and determining percent surface area decayed after four days in a mist chamber. Tubers of the cultivars differed widely in resistance to bacterial soft rot. The ranking of the resistance of tubers from different cultivars to bacterial soft rot was similar for both soils, although disease severity in tubers from a particular soil type varied with the season. Of the cultivars tested, tubers of Butte, Russet Burbank, and Nor-gold Russet were ranked as the most resistant, whereas tubers of Redsen, Norchip, Norland and Belchip were rated as the most susceptible. Tubers of Rhinered, Red La Soda, Superior, Pontiac, Atlantic, and Nooksack were intermediate in resistance. Neither calcium concentration in medullar tissues nor dry matter of potato tubers alone could be correlated with ranking of the cultivars with respect to severity of bacterial soft rot. However, a multiple linear regression model incorporating both variables indicated that tubers with a high content of both calcium and dry matter were likely to be less susceptible to bacterial soft rot than were tubers with lower percentages of these variables.     

Production of potato minitubers by repeated harvesting: Effects of crop husbandry on yield parameters

Summary Minitubers can be produced in large quantities by repeated harvesting of tubers from in vitro propagated plantlets at 4, 7 and 10 weeks after transplanting to the glasshouse at high plant densities. Yield parameters of minitubers can be manipulated by crop husbandry. By supplying nutrients or using a square plant arrangement, minituber yield increased. Effects on numbers of tubers were cultivar-dependent. Changing plant density from 50 to 800 plants per m² or the minimal diameter of harvested tubers from 5 to 12 mm did not significantly affect tuber yield per m². Higher plant densities resulted in more tubers per m² but fewer tubers per plant. Removing smaller tubers greatly increased the number of small tubers, but did not affect yield and number of tubers in larger grades. Crop husbandry techniques affected minituber yield mainly through their effects on leaf area duration, and the number of minitubers through their effects on growth of tubers to a harvestable size.     

Evaluation of thiabendazole and pentachloronitrobenzene for control of the Rhizoctonia disease complex on white potato (Solanum tuberosum L.)

Thiabendazole (TBZ) and pentachloronitrobenzene (PCNB) alone and in combination were laboratory, greenhouse, and field tested during a five-year period (1977-1982) for their effectiveness in reducing incidence and severity of damage caused byRhizoctonia solani to white potato (Solarium tuberosum). Growth ofR. solani on amended potato dextrose agar was prevented at 7 ppm TBZ and 80,000 ppm PCNB. Tuber-borne sclerotial germination and hyphal growth were prevented following seed treatment with 6,000 ppm TBZ, and severely inhibited by combination treatments of 12,500 or 50,000 ppm PCNB and 1,500 ppm TBZ. Seed treatments which provided the most effective field control ofR. solani were combinations of PCNB (50,000, 25,000 ppm) and TBZ (1,500 ppm), followed by TBZ alone (6,000 ppm) and PCNB alone at rates of 50,000 ppm or above.     

Some unique benefits with sudangrass for improved U.S. #1 yields and size of Russet Burbank potato

Three studies provided additional knowledge of beneficial effects of sudangrass for yield and quality increases of the Russet Burbank potato. Two of these studies showed significant increases of both U.S. #1 and smooth tubers > 280 g following green manures of sudangrass. These sudangrass (HS-33) effects did not differ from a sorghum-sudan hybrid (Trudan-8). When a sudangrass green manure was compared with a fallow treatment, results of the first study showed mean yield increases of 36% for U.S. #1 tubers > 280 g and yields of a second study by 34% for U.S. #1 tubers. This same sudangrass treatment outperformed green manures of either Austrian winter pea, barley, or sweet corn by increased U.S. #1 yields that ranged from 27% to 61%. By several lines of evidence, these benefits were found to extend beyond the effect of Verticillium suppression. Soil N was significantly increased following green manures of sudangrass, and these increases were in turn negatively correlated with wilt incidence and positively correlated with yields of both U.S. #1 tubers and tubers > 280 g. Additional benefits also included significant increases of tuber grade percentages for marketable tubers and of smooth tubers > 280 g. Benefits from sudangrass green manures beyond the effects of Verticillium suppression became further evident following a greenhouse study that involved field soil and sudangrass that had been grown in the same field. This study corroborated both field experiments by showing increased yields with green manures of sudangrass that approximated 5.5 t ha^-1 dry wt. As with the field studies, these yield benefits also extended beyond the effects of Verticillium suppression and were closely associated with significant increases ofFusarium equiseti, F. oxysporum, andF. solani. Throughout all studies, sudangrass green manures significantly increased microbial activities with increased populations ofFusarium spp. and increased concentrations in soil of mineralizable N, organic P, K, Mn, along with the percent soil organic matter -all factors that could have contributed to significant increases of yield and quality.     

Effect of pentachloronitrobenzene soil treatment on flavor of potatoes

Pentachloronitrobenzene (PCNB) was applied to the soil prior to planting at the following rates of active ingredient per acre: 50 pounds at Maine and at North Dakota in 1959, 12.5 and 25 pounds at North Dakota and 20 pounds at Maine in 1960, and 50 pounds at New Jersey in 1961. One or more panels evaluated the flavor of the potato samples. No off-flavors were reported when potatoes were grown in soil treated with 12.5 or 25 pounds of active PCNB per acre at the one location. Off-flavors were found with PCNB treatment with 20 pounds active ingredient at one location and with 50 pounds active ingredient per acre at three locations.     

Potato blackleg disease

Blackleg, a bacterial soft-rot of potatoes caused byErwinia atroseptica, has been recognized since the turn of the century as a disease capable of causing tremendous losses to the crop in the field or in storage. The pathogen is both seed- and soil-borne, and generally attacks the seed piece through wounds caused by insect larvae, fertilizer burns, frost injury, bruises, or lesions caused by other pathogenic bacteria and fungi. Infection is increased by low temperature and high moisture, especially in the soil. These conditons are less than optimum for the pathogen, but are less favorable for the infected plant, as they slow normal growth and prevent formation of protective cork tissue which would restrict the spread of the infection. Partial control of this disease can be effected by using seed free from disease, sanitation, crop rotation, planting in well-drained soils, prevention of any wounds or diseases which would permit entry of the pathogen, planting resistant varieties, seed treatment, and proper storage conditions for freshly dug tubers and cut tubers if they cannot be planted immediately.     

Comparative performance of different-sized seed tubers derived from true potato seed

The growth and yield of plants from different-sized seed tubers derived from true potato seed were evaluated on a per stem, per plant, and per unit area basis using either single or multiple-sprout tubers. In single-sprout tubers, haulm dry weight per stem 47 days after planting was greater in the 40–60 g tubers when compared with that in the 5–10 g or the 10–20 g tubers. This resulted in greater tuber weight per stem in the 40–60 g tubers throughout the growing season. The number of tubers per stem was not affected by seed tuber size. In multiple-sprout seed tubers of increasing size, total tuber number and total tuber weight, as well as weight of those tubers larger than 45 mm, increased on a per plant basis but decreased on a per stem basis. At different rates of planting, 1–5 g seed tubers produced smaller tubers than 5–10 g or 10–20 g seed tubers. Increased rate of planting resulted in non-significant yield increases per unit area in plots planted with 1–5 g seed tubers. The yield increases were significant when 5–10 g and 10–20 g seed tubers were planted at higher rates. The number of main stems per unit of seed tuber weight was five times greater in 1–5 g tubers compared with that in 40–60 g tubers. This resulted in low seed weights per hectare when small tubers were planted and in a high ratio of harvested to planted tuber weight.     

Growth-room and field studies with seed tubers treated with ethylene and 1-methylcyclopropene (1-MCP) during storage

Based on ethylene management in potato storage, we hypothesized that the applied treatments would modify number of sprouts per seed tuber. Thus, in combination with in-row spacing (closer for seed, wider for processing) in the field treatments will give either (1) a high number of small tubers destined for seed use, or (2) a relatively smaller number of large, uniform tubers suitable for processing. A three-year study (2001–2003), conducted with two french fry processing cultivars, Russet Burbank (RB) and Shepody (SH), aimed at the development of a novel modified atmosphere seed tuber storage treatment. Seed tubers were stored at 4 C from October to May of each year in a cold room under five modified atmospheric regimes: (1) air ventilation only (Control); (2) 4 µl L^?1 ethylene applied continuously beginning in November and (3) beginning in February; (4) 1 µ1 L^?1 MCP (1-methylcyclopropene) applied as a gas for 48 h only in early December followed by continuous 4 µl L^?1 ethylene and (5) MCP alone applied as above. Each year, once a month (mid-January until end of April), a number of seed tubers was taken from each storage treatment, planted to pots and grown for 4 wk in a growth-room. In these studies, shoot emergence from the ethylene-treated seeds of both cultivars occurred significantly earlier, giving higher number of stems per tuber and stolons per stem than Control and MCP treatments. Moreover, the time to emergence after planting decreased with the increased length of storage. Field studies that were conducted from the end of May (planting) until October each year, produced similar trends (although not significant atP≤0.05) and resulted in a higher number of tubers per stem. In RB at the closer in row spacing (30 cm) used for seed production, ethylene enhanced yield of smaller tubers in the 30- to 115-g and 115- to 300-g categories. The ethylene storage treatments also increased tuber number per plant, but not the total mass of harvested potatoes. The MCP treatment, in combination with the wider in-row spacing (40 cm) used for the production of processing tubers, significantly increased the percentage of large tubers (>300 g). In SH, contrary to RB, the ethylene treatments did not alter tuber size distribution and the application of MCP reduced tuber size rather than increasing it. Results from this study suggest that both ethylene and MCP can be used in seed potato storage to influence the tuber size distribution of the crop from that seed.     

Hypoxic stress inhibits aerobic wound-induced resistance and activates hypoxic resistance to bacterial soft rot

Resistance to bacterial soft rot in potato tubers maintained aerobically was induced by wounding tubers 4 to 24 h prior to inoculation withErwinia carotovora subsp.carotovora. This wound-induced resistance phenomenon was blocked by hypoxic stress. An hypoxia-induced resistance mechanism also was detected: tubers acclimated to a hypoxic environment were resistant to rot when inoculated with aerobically grownE. c. subsp.carotovora and incubated in atmospheres made hypoxic by argon or nitrogen. With increased pretreatment, hypoxia-induced resistance approached the levels of resistance observed in tubers inoculated with aerobic-adapted bacteria and incubated aerobically. Hypoxia-adaptedE. c. subsp.carotovora overcame hypoxia-induced resistance.     

Effects of gypsum,sulfur, terraclor and terraclor super-x for potato scab control

An investigation was made to determine possible effects of gypsum and sulfur for control of common scab of potato [Streptomyces scabies (Thaxt.) Waksman and Henrici] in a highly buffered calcareous soil. This investigation included a comparison of the effectiveness of gypsum and sulfur with Terraclor and Terraclor Super-X. Both gypsum and sulfur reduced potato scab and measurements indicate that change of soil pH was slight (0.1–0.4 pH reduction). Band applications of sulfur in the sulfate (gypsum) or elemental form were effective at 600 lbs/A (672.5 Kg/ha) but not at lower rates. The weight of tubers thrown out of grade with scab was reduced by 53% with the effective sulfur rate. Treatment effects of gypsum (600 lb S/A-672.5 Kg/ha) were not significantly different from sulfur dust (600 lb/A-672.5 Kg/ha), Terraclor or Terraclor Super-X (both at 25.0 lb PCNB/A-28.0 Kg/ha). Tissue analyses of tuber peelings showed a significant reduction in calcium from treatments involving sulfur and gypsum, indicating that calcium levels in tuber peelings were positively correlated with scab susceptibility.     

Effects of Soil Water Level,Black Dot (Colletotrichum coccodes) Infested Soil and Nutrient Depletion on Potato in a Controlled Environment

The effects of soil water level and soil infested or not infested with Colletotrichum coccodes were quantified and compared on Umatilla Russet potato in repeated greenhouse trials. Nitrogen levels in leaflets and tuber yield differed significantly for effect of water level but there was no effect for soil infestation in both trials. More leaflet N as measured by chlorophyll and less tuber yield occurred in the low than the medium and high soil water treatments. Number of progeny tubers was not affected by C. coccodes but numbers were significantly less for the low water level than the high water level in one trial. Root weight was significantly reduced by C. coccodes in both trials and was significantly less in the high than the low and medium soil water levels in one trial. Incidence of infected progeny tubers was significantly reduced in infested soils for the low soil water compared to the medium or high soil water levels in one trial. The effect of increasing levels of water in infested soils had large and significant increases for percentage of stem area with sclerotia in both trials. Managing soil water by not overwatering in irrigated potato fields in the presence of C. coccodes may reduce black dot severity and quantity of sclerotia that potentially can overwinter and serve as sources of infection for subsequent crops. Analyses demonstrated a potential for significant associations between plant and disease variables not evidence for cause and effect.     

Extraction ofclaviba cter michiganensis subsp.sepedonicus from composite samples of potato tubers

The presence ofClavibacter michiganensis subsp.sepedonicus was detected by immunofluorescence and ELISA in diluent in which cores from 200 potato tubers had been incubated on a rotary shaker. By this procedure the ring rot pathogen was detected in composite samples from naturally infected tubers and tuber samples “spiked” with infected tissue or a pure culture of the pathogen. Populations of saprophytic bacteria increased about 100-fold in the diluent during 18 h of incubation but did not interfere with serological detection of C.m. sepedonicus. Some of the results suggest thatC. m. sepedonicus cells multiply during incubation of tuber samples. Extraction of ring rot bacteria from potato tuber tissue by incubation on a rotary shaker requires little work and minimizes the amount of plant tissue in the extract compared to the standard extraction procedure involving maceration and differential centrifugation.     

Evaluation of immunofluorescence with monoclonal antibodies for detecting latent bacterial ring rot infections

Corynebacterium sepedonicum was detected in symptomless potato stems and tubers with immunofluorescence using monoclonal antibodies specific for the bacterial ring rot pathogen. The concentration of bacterial cells in potato tissue preparations ranged from >500 cells/microscope field to 1 cell per preparation. Symptomless tubers containing ring rot bacteria planted in field plots yielded plants with ring rot symptoms, plants with latent ring rot infections, or plants with no detectable levels of ring rot bacteria. Tubers with the greatest number of bacteria were most likely to develop plants expressing ring rot symptoms, but even some seed tubers with a low number of bacteria developed into plants with symptoms. Some seed tubers with high levels of ring rot bacteria produced plants with only low numbers ofC. sepedonicum.