Influence of cultural factors on alfalfa seedling infection by Pythium debaryanum Hesse

It is well recognized that considerable care must be exercised on some soils to establish stands of small-seeded legumes, notably alfalfa and red clover and sometimes sweet clover. Farmers generally are aware of the necessity of sowing a good grade of seed of a hardy variety on a well-prepared seedbed under a light nurse crop, after the soil, if acid, has been limed. The common rate of seeding alfalfa is 10-15 pounds per acre, which, with good-quality seed, provides for 50-75 seeds per square foot. Second year stands in Iowa, however, rarely contain more than 10 plants per square foot. Obviously a reduction of any part of an alfalfa stand loss, with its accompanying hazard of complete failure, would be of real benefit to the Iowa farmer. The role of Pythium in destroying alfalfa seedling stands on three acid Iowa soils was first pointed out by the author (1, 2) in two short preliminary papers in 1934 and 1935. Pythium was observed to produce necrotic lesions on germinating seed and alfalfa seedlings more commonly on slightly acid Clarion loam, Webster loam and Tama silt loam than on two similar areas of neutral Webster loam and Webster silty clay loam. At 9°C. fewer alfalfa and alsike clover seedlings became infected than at 20° -25 ° C. Plantings of alfalfa and alsike clover on steamed and formaldehyde-treated acid soil yielded as many or more healthy alfalfa seedlings than similar plantings on neutral field soil. Alsike seedlings seemed more resistant to Pythium than alfalfa seedlings at 20°-25° C. The prevalence of infection of alfalfa seedlings in acid soils at moderate (15°-30° C.) temperatures is comparable to the situation recently reported (3) from sugar beet seedling damping-off studies in northern Iowa

Sorghum Seed Treatment

Sorghum has since 1930 become a major South Dakota crop. One of the highly beneficial farm practices involved in successful sorghum production in this state is seed treatment. Covering the seed with a mold-killing dust before planting has a threefold effect: 1. It completely controls smut. Smutted heads develop only on plants grown from seed infected during germination by smut carried on the seed. By killing the seed-borne smut, seed treatment prevents infection and insures a stand of smut-free plants. 2. It prevents seed decay by molds in cold, wet soil. Sorghum stands often fail in South Dakota when the seed lies in cold wet soil during unseasonably cold weather. 3. It kills molds on the seed. These molds usually develop during storage. Moldy seed is less likely than clean seed to produce a satisfactory stand. This circular tells what seed treatment materials to use for these purposes and gives the results of their use in experiments at the South Dakota Station

Tomato Leaf Spot Diseases in South Dakota

Tomato leaf spots in 1942 and \u2743 caused low yields and poor quality of fruit in many eastern South Dakota gardens. Successful control of these diseases must be based on preventing early infection of the plants and the spread of the organisms which cause them. This circular describes briefly the two leaf spot diseases of tomatoes common in South Dakota. Control measures for each are listed on page 7

The Barberry

Barberry plantings are a host for stem-rust that spread to crops and must be eradicated. This pamphlet explains why and how to stop the spread of bayberries

Treat Seed Grain

Discusses how to control seed and soil diseases by treating seed grain. It describes the equipment and chemicals used to for preventing these diseases and increase yields

Mop Up those Vegetable Diseases

Discusses how to prevent disease from taking over a home garden. It provides tips on rotating plantings, treating seeds, and spraying

The Effect of Surfaces on the Tunneling Density of States of an Anisotropically Paired Superconductor

We present calculations of the tunneling density of states in an anisotropically paired superconductor for two different sample geometries: a semi-infinite system with a single specular wall, and a slab of finite thickness and infinite lateral extent. In both cases we are interested in the effects of surface pair breaking on the tunneling spectrum. We take the stable bulk phase to be of $d_{x^2-y^2}$ symmetry. Our calculations are performed within two different band structure environments: an isotropic cylindrical Fermi surface with a bulk order parameter of the form $\Delta\sim k_x^2-k_y^2$, and a nontrivial tight-binding Fermi surface with the order parameter structure coming from an anti-ferromagnetic spin-fluctuation model. In each case we find additional structures in the energy spectrum coming from the surface layer. These structures are sensitive to the orientation of the surface with respect to the crystal lattice, and have their origins in the detailed form of the momentum and spatial dependence of the order parameter. By means of tunneling spectroscopy, one can obtain information on both the anisotropy of the energy gap, |\Delta(\p)|, as well as on the phase of the order parameter, \Delta(\p) = |\Delta(\p)|e^{i\varphi(\p)}.Comment: 14 pages of revtex text with 11 compressed and encoded figures. To appear in J. Low Temp. Phys., December, 199

A Better Garden Here\u27s How

Tips for planting a garden that will feed a family of five that will supplement the shortages of canned vegetables for civilians. It also has a listing of vegetables and when and how to plant them, and how to control vegetable diseases

Prunus hortulana: A Virus-Free, Nonsprouting Understock for Hardy Plums and Ornamental Prunus

For many years, nurseries in the North Central States have been propagating hardy plums and ornamental Prunus on Prunus americana seedling understocks. Hardiness and compatibility with many scion varieties, together with general availability, ease in growing and handling, and suitability for the budding operation, are recognized attributes which have encouraged almost universal use of this species for many years. From a nursery production standpoint it leaves little to be desired

Quasiparticle Bound States and Low-Temperature Peaks of the Conductance of NIS Junctions in d-Wave Superconductors

Quasiparticle states bound to the boundary of anisotropically paired superconductors, their contributions to the density of states and to the conductance of NIS junctions are studied both analytically and numerically. For smooth surfaces and real order parameter we find some general results for the bound state energies. In particular, we show that under fairly general conditions quasiparticle states with nonzero energies exist for momentum directions within a narrow region around the surface normal. The energy dispersion of the bound states always has an extremum for the direction along the normal. Along with the zero-bias anomaly due to midgap states, we find, for quasi two-dimensional materials, additional low-temperature peaks in the conductance of NIS junctions for voltages determined by the extrema of the bound state energies. The influence of interface roughness on the conductance is investigated within the framework of Ovchinnikov's model. We show that nonzero-bias peaks at low temperatures may give information on the order parameter in the bulk, even though it is suppressed at the surface.Comment: 14 pages, PostScrip