Effects of soil fumigation with Telone-C on the field inoculum potential of tobacco rattle virus and potato yields

Two Julesburg sandy-loam fields in Weld County, Colorado, with a history of Corky Ringspot (CRS) caused by tobacco rattle virus (TRV) were injected with Telone-C as fall or spring applications and planted to potatoes. Deep soil sample cores taken from the experimental fields were planted toNicotiana tabacum L. var. Samsun serving as TRV bait and indicator plants. Systemic infection of bait plants and assay of the bait plant roots for TRV indicate that potential TRV inoculum was present which escaped the effects of fumigation treatments. TRV was found to be widely but erratically distributed throughout the experimental fields. The low incidence of CRS in tubers harvested from the treated fields suggests that fumigation may have short term benefits but potential inoculum exists which could lead to infection after the effects of fumigation have dissipated. The total yield of tubers was increased in the two cultivars planted (Norgold and Norland) in the fumigated fields receiving spring or fall applications. The yield of U.S. No 1 Grade potatoes in the Norland cultivar was increased significantly by both fall and spring fumigation. These yield increases were directly related to the reduced incidence ofVerticillium wilt observed in the fumigated soils and reported as a personal communication from unpublished data.     

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.     

Seed potato quality as influenced by high temperatures during the growth period. 2. Sprouting pattern in several cultivars in response to storage temperature

Summary Locally grown seed tubers of nine varieties developing in spring or in autumn in a semi-arid region were examined for length of dormancy and for sprouting response. In spring, high temperatures during the last part of tuber development markedly shortened the dormant periods of tubers in comparison with tubers of the same varieties developing in autumn. The sprouting behaviour of tubers indicated that it is a varietal characteristic influenced by the change in environmental conditions during tuber development and storage. On tubers developing in spring and stored at high temperatures, three sprouting patterns were defined: a) apical dominance, characterized by the evident development of the apical sprout and less than 10% sprouting of the non-apical buds; b) apical influence, the apical sprout well developed and 10–20% sprouting of the non-apical buds; and c) simultaneous sprouting of 3 or 4 sprouts of similar size per tuber. It is suggested that apical dominance is a relative rather than an absolute phenomenon. The extent of dominance depends upon the variety's response to the high temperatures during tuber growth and storage. Contribution from the Agricultural Research Organization, Beit Dagan, Israel, 1979 Series, No 301.     

Area control of the green peach aphid on peach and the reduction of potato leaf roll virus

Peach trees in a 500-mile² (1295 sq. K) area were sprayed during April and May each year from 1966 to 1969 to control the wingless fundatrix form ofMyzus persicae (Sulzer) after the overwintering eggs had hatched and before subsequent generations of the aphids had developed wings and migrated to summer host plants. The results were monitored from 1966 to 1971 by using about 60 yellow water trap pans each year to collect winged aphids in the control area. Also, aphids were counted weekly in about 30 potato fields each year. Samples of potato tubers collected from the 30 fields (and from 34 other fields in 1965) were indexed for net necrosis and then planted and indexed for chronic leaf roll. The early spraying reduced the populations of winged aphids collected in traps in May and early June 1966–1969 by about 60% compared with the post-spray years (1970–1971). The amount of net necrosis found in potato tubers from the control area was reduced from 11 % in 1965 to slightly more than 3% from 1967 through 1969 and the chronic leaf roll in plants was reduced from 43% in 1965 to about 10% for the same years. Only after two years of spraying was there evidence of a significant reduction in the spread of the virus; similarly, not until 2 years (1970 and 1971) following the end of the spray program did the virus increase significantly.     

Seed potato quality as influenced by high temperatures during the growth period. 1. Effect of storage temperature on sprout growth

Summary In the Negev area of Israel potatoes are grown in two seasons of the year: spring and autumn. Locally grown seed of cv. Up-to-Date prepared for the autumn season are grown in the spring under high-temperature conditions during the last part of the growth period. The response to storage temperature treatments consisted of different degrees of sprouting. Temperatures that encouraged bud development (12–22°C) shortened the dormant period of the tubers by about a month, and usually there is clear apical dominance. However, increasing length of the apical bud was positively correlated with storage temperature. Partial loss of apical dominance was obtained when the tubers were held at a low temperature (4°C) for at least two months after lifting. After transfer of the tubers to high temperatures for another month, there were 3 or 4 sprouts per tuber. The physiological age of seed tubers developing in the semi-arid region is discussed. Contribution from the Agricultural Research Organization, Beit Dagan, Israel 1979 Series, No 300.     

Growth and yield studies of potatoes developed in a semi-arid region 1. Yield response of several varieties grown as a double crop

Summary The yielding capacity of European potato varieties was tested in the spring and the autumn. The environmental characteristics for the spring crop (February–June) are increasing day length and temperature from planting to harvest, with the opposite for the autumn crops (August–December). In the spring crop, using imported seed tubers of about 5–6 months' chronological age, the stem density of different varieties varied between 120 000 and 240 000 per ha, and the weekly yield rates (total yield/growth period) were 2.6 and 4.7 t/ha. In the autumn crop, when local seed tubers of 3 months' chronological age were planted, the stem density was 2–3 times lower and the weekly yield rates were between 1.6 and 3.9 t/ha. Two groups of potato varieties were selected according to their yield performance as being suitable: a) for the spring crop cvs. Up-to-Date, Désirée and ZPC 71E207; and b) suitable for the autumn crop cvs. Désirée, Draga, Gulliver, Spunta, Ropta A3802, ZPC 71E277, and Cardinal. The variability in yield response of theS. tuberosum varieties to the high temperatures and short photoperiods of the semi-arid environment is discussed. Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 280-E, 1980 series.     

Influence of water and soil salinity on emergence and early development of potato (Solanum tubersum L.) cultivars and effect of physiological age of seed tubers

Summary Applying saline solutions (EC 3.2 up to 7.0 dS/m) to seed tubers of different cultivars planted in tuff delayed shoot emergence and root and shoot development. Fresh weight of most cultivars was decreased by 60% but cv. Serrana Inta was more tolerant to salinity and fresh weight was decreased by 20%. When planted in 500 cm³ pots containing loessial soil some seed tubers rotted and plant growth was severely inhibited, possibly because soil aeration was impeded. Physiologically ageing seed tubers for 33 days at 6°C decreased sensitivity of most cultivars to moderate salinity whereas ageing for 68 days increased sensitivity to high salinity. Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 2977-E, 1990 series.     

Hill Shape Effect on Yield,Quality, Stolon Length and Tuber Orientation of Two Potato Cultivars

Potato (Solanum tuberosum L.) cultivars are mostly planted using similar seed piece planting depths and hill shapes even though cultivars have unique tuber and stolon characteristics. A hill-shape study was conducted at Aberdeen, Idaho to determine the effects of hill shape on yield and field-green tuber yields and quality along with stolon length and tuber spatial orientation for two potato cultivars, 'Defender' and 'Summit Russet.' Plots were planted in late April to early May. Prior to emergence four hill shapes were formed: 1) plant-and-drag, 2) broad, 3) normal, and 4) peaked. Defender had higher total yield with the broad hill, but there were no differences among the remaining three hill shapes. For Defender, U.S. No. 1 yield was lower with the plant-and-drag hill shape, and the normal and peaked hills produced lower field-green tuber yield. Hill shape had no effect on total, U.S. No. 1, or field-green tuber yields of Summit Russet. The peaked hill resulted in a deeper uppermost tuber for Defender, while the uppermost tuber was deeper in the normal and peaked hills for Summit Russet. The broad hill resulted in a larger average tuber size for Defender, but hill shape had no effect on tuber size for Summit Russet. Total number of tubers per plant, stolon length and tuber spatial orientation were not affected by hill shape for either cultivar. Hill shape and height are important considerations in maximizing yield of saleable tubers, so needs to be customized according to cultivar-dependent stolon length and tuber orientation characteristics.     

Effect of whole seed tuber size and pre-plant storage conditions on yield and tuber size distribution of Russet Burbank

Field experiments were conducted in 1995, 1996, and 1997 at Agriculture and Agri-Food Canada’s Harrington Research Farm to assess the effect of whole seed tuber size and pre-plant seed storage conditions on processing yield (> 51 mm dia.) of potato (Solanum tuberosum L. cv Russet Burbank). Following commercial storage, seed tubers were stored at 4.4 C then subjected to one of three pre-plant treatments: (1) planted directly from storage, (2) held at 10 C for 3 wk before planting, or (3) green-sprouted for 3 wk before planting. Five sizes of whole seed were used (28, 42, 56, 70, and 84 g) with a variable size cut seed treatment added for comparison. Plots were harvested 138,134, and 131 days after planting in 1995, 1996, and 1997, respectively. Cut seed produced a higher yield of tubers > 51 mm diameter in comparison to all whole tuber seed sizes, with the exception of the 28 and 56 g sizes. In terms of total yield, the 28and 42-g whole seed tubers yielded significantly less than all other seed sizes examined. Warming or greensprouting seed tubers prior to planting did not increase tuber yield. The larger whole seed tuber sizes tended to result in greater numbers of stems and tubers per plant. To maximize marketable yield of Russet Burbank planted from whole seed tubers, it is recommended that the seed be between 28 and 42 g in size. Accepted for publication 25 May 2004.     

Role of seed tubers in the spread of plant pathogenicStreptomyces and initiating potato common scab disease

The influence of tuber-borne pathogenicStreptomyces on potato common scab incidence in daughter tubers was examined under micro-plot conditions. Visually healthy tubers, surface-disinfested healthy tubers, and tubers with 25% scab coverage were planted in pasteurized soil. At 30, 57, and 93 days after planting, soil and belowground plant parts were sampled from various zones around the mother tuber. The total population of actinomyctes was determined by plating on a semiselective medium, and colonies of pathogenicStreptomyces were identified using polymerase chain reaction (PCR) targeting thetxtA gene. At day 30, pathogenicStreptomyces populations were below detectable levels, whereas by day 93, measurable levels were present on the belowground plant parts and in soil adjacent to scabby mother tubers at 10⁴ to 10⁵ CFU g^?1 soil. Incidence of scab in the progeny tubers was 89% at harvest. Progeny tubers produced by visually healthy seed tubers had an incidence of 60% scab and substantial populations of pathogenicStreptomyces were present in the zone near the mother tuber (10⁴ CFU g^?1 soil). Plots planted with surface disinfested seed tubers had a very lowStreptomyces population in the tuber zone and yielded 100% marketable tubers. A perfect correlation (r = 1.00) was found between the population densities of pathogenicStreptomyces in the root zone and daughter tuber disease incidence indicating that measurement of such populations in the field can serve as an excellent predictor of scab disease. After harvest, populations of pathogenicStreptomyces (10⁶ to 10⁷ CFU g^?1 lesion tissue) remained high on the mother tubers.     

Effect ofErwinia carotovora subsp.atroseptica on yield of potatoes from cut and uncut seed tubers in Valencia

Summary The effect on the development of blackleg symptoms and on yield of inoculating seed tubers of 15 cultivars withErwinia carotovora subsp.atroseptica (Eca) was investigated. Tubers were planted either whole or as pieces. Eca inoculation reduced the mean yield per plant by 8% for whole tubers and by 12% for cut tubers. There was no correlation between blackleg symptoms and yield loss.     

Growth and yield of potato plants grown from microtubers in fields

Despite many reports of thein vitro production of microtubers, little is known about plant growth and yield from microtubers planted in the field. This study clarified differences in growth and yields between potato plants grown in the field from microtubers and from conventional seed tubers. The experiments were performed at Hokkaido University, Japan, over four years. Conventional seed tubers of about 50 g and microtubers of two sizes (0.5–1.0 g and 1.0–3.0 g) of the latematurity cultivar Norin 1 were planted, and plant growth and tuber yields were analyzed. The microtuber plants had a lower initial increase in root and leaf area index than conventional seed tuber plants, but had the same leaf area index after about 40 days from emergence. The first tuber formation in microtuber plants was about 7 days later than in conventional seed tuber plants, while tuber bulking occurred about 14 days later in microtuber plants. Consequently, the onset of tuber weight increase was later in microtuber plants, but the rate of increase thereafter was similar between conventional seed tuber and microtuber plants. At harvest the tuber fresh weight of microtuber plants was 82% that of conventional tuber plants, suggesting a potential for using microtubers for field planting.     

Rapid seed multiplication by planting into beds micro tubers and in vitro plants

Summary Micro tubers of 3 weight categories with means of 0.63 g, 1.25 g or 2.50 g and in vitro plants were planted in nursery beds at densities of 24 and 48 plants per m². The average tuber numbers and tuber weights were, respectively, 38% and 17% higher at 48 than at 24 plants per m². In vitro plants produced significantly more but smaller tubers than did plants grown from micro tubers. Plants grown from the larger micro tubers produced a similar number of tubers but larger ones than did plants grown from small micro tubers. Tuber yields and multiplication rates are discussed.     

The effect of water stress on the yielding capacity of potato crops and subsequent performance of seed tubers

Summary The effect of water stress on yielding capacity of potatoes was studied in 3 years using four different levels of soil water potential (0.7, 1.9, 3.4 and 7.8 atm.) in experiments in specially adapted structures that excluded uncontrolled water supply. Seed tubers from these crops were planted in the following years to investigate effects of water stress on their subsequent performance. Limited soil moisture availability decreased yield and the number and size of tubers. The growing period was shortened by 1–4 weeks and dormancy period by 2–8 weeks. In the following year, seed produced under conditions of moisture stress gave plants with 20% fewer stems. 24–33% less yield, 18–22% fewer tubers and 19–22% fewer large tubers than plants from seed produced under abundant water supply. It is concluded that the yield potential of seed tubers can be improved by careful attention to the availability of soil moisture during their production.     

Effect of Potato Microtuber Size on the Growth and Yield Performance of Field Grown Plants

Abstract

To examine the effect of the size of the potato microtuber (MT) produced in vitro on the posterior field performance, we examined the growth and yield of the late maturity cultivar Norin 1 using four sizes of MT: 0.3–0.5 g, 0.5–1 g, 1–3 g and 3–5 g, and conventional seed tubers (CT) (approximately 50 g). The experiment was conducted at Hokkaido University, Sapporo Japan in 1998 and 1999. The tubers were planted in May of each year, in a randomized block design with three replications. Plants from MT lighter than 0.5 g showed a slower initial leaf and tuber growth than heavier MT, but around the full flowering stage there was no significant difference with the MT size in leaf or tuber growth. CT plants showed higher initial leaf and tuber growth compared with MT plants, especially in 1999. No differences in growing period, number of tubers, and tuber fresh and dry yield were observed with the MT size. However, in 1999, the growing period was longer and tuber fresh and dry yields at harvest were higher in CT plants. MT of all sizes used in the study can be used for direct field planting, but more studies are needed to increase the yield stability of MT plants.     

The effect of harvest date and tuber-borne sclerotia on the severity ofRhizoctonia disease of potato

Experiments performed in 1976 and 1977 examined the effect of harvest date on the development of tuber-borne sclerotia and the effect of these sclerotia onRhizoctonia disease severity of potato. Results from tubers harvested at seven weekly intervals in 1975 indicate maximum sclerotial development occurred 3–4 weeks after vine killing. When these tubers were planted the following year, few differences occurred in disease severity of stems and stolons with respect to prior harvest date. However, the tubers which had remained in the ground 4–7 weeks after vine killing in 1975 produced the largest and greatest number of sclerotia on progeny tubers harvested in 1976. Experiments in 1976 and 1977 demonstrated that tubers with approximately 20% sclerotial coverage produced stems and stolons with significantly more severeRhizoctonia disease compared to tubers with no visible sclerotia. Sclerotial coverage on tubers of less than 20% did not significantly increase disease severity.     

Comparative performance of three small seed tuber sizes and standard size seed tubers planted at similar stem densities

Summary Small seed tubers of 1–5 g, 5–10 g and 10–20 g were planted at the same sprout densities as standard size seed tubers of 40–60 g in order to give similar stem densities. Early ground cover by foliage, total yield, and yield of tubers >45 mm were consistently greater in plots planted with larger seed tubers. The effect of seed tuber size on yield and tuber number per stem varied between years but 1–5 g seed tubers always gave lower yields per stem than larger seed tubers. Reducing the spacing between rows from 90 cm to 60 cm and maintaining the same sprout density was more effective in increasing yields from small seed tubers than increasing sprout density from 20 to 40 sprouts per m² by reducing plant spacing within the row.     

Tillage and seed-sprouting strategies to improve potato yield and quality in short season climates

Management practices that accelerate crop development and allow earlier harvest would be beneficial in short-season potato (Solanum tuberosum L.) production areas. Yield and quality of the potato cultivar ‘Russet Burbank’ were evaluated in a 2-yr study in northern Maine to determine effects of soil tillage and seedsprouting treatments designed to dry soil early in the spring and hasten seed emergence. The tillage treatments, consisting of fall raised bed (RB), fall ridge till (RT), and spring chisel plow (CH), were tested in combination with green-sprouted and non-sprouted seed tubers on a Caribou gravelly loam (coarse-loamy, mixed, frigid,Typic Haplorthod). Plants from green-sprouted seed emerged earlier than from non-sprouted seed tubers (87%-96% vs 21%-37%, respectively, at 18 days after planting [DAP] in 2000; and 73%-88% vs 18%-23%, respectively, at 20 DAP in 2001). Green-sprouted seed tubers in RB yielded 4.6 to 5.9 T ha^-1 more than nonsprouted seed tubers in RB. However, non-sprouted seed tubers yielded higher than green-sprouted seed tubers in RT by 2.9 to 4.2 T ha^-1 and in CH by 1.1 to 4.1 T ha^-1. Similarly, green-sprouted seed tubers in RB and nonsprouted seed tubers in RT and CH produced higher marketable yield, greater tuber length, and greater tuber diameter than the corresponding seed-sprouting treatment. In the comparatively wetter year (2000), the use of green-sprouted seed tubers in RB significantly increased total and marketable yields, and produced longer and larger tubers than all other treatments. However, in 2001 (relatively dry year), yield and quality from green-sprouted seed tubers in RB did not differ from non-sprouted seed in RT or CH. Green-sprouted seed produced fewer sunburned and rotten tubers, but more misshapen tubers than non-sprouted seed in RB tillage. The technique of producing Russet Burbank potatoes in raised beds is a promising system in regions with short growing seasons for enhancing early soil drainage during spring and improving soil water retention during critical periods of crop growth and development.     

The effect of seed-and soilborne inoculum ofColletotrichum coccodes on the incidence of black dot on potatoes

Summary Soil in a potato field naturally infested with black dot (Colletotrichum coccodes) was fumigated with methyl bromide at 126 g m⁻² or left unfumigated. Potato seed tubers (cv. BP1) uninfected, lightly infected (1–25% surface affected), severely infected (26–100% surface affected) and severely infected withC. coccodes but dusted with prochloraz manganese chloride as Octave 2.5% DP at 750 g per 100 kg seed were planted in fumigated and unfumigated soil. When harvested, the incidence of black dot on the progeny of infected seed planted in unfumigated soil was twice that of progeny in fumigated soil, with progeny of uninfected seed having a 68.5 times higher disease incidence in unfumigated soil. Black dot on progeny tubers was reduced by pre-treatment of seed with prochloraz in fumigated soil only. With black dot infested fields, planting disease-free seed or treating seed with fungicides would not decrease disease on progeny tubers.