Reiner Bonde

The effect of latent mosaic (virus x) on yield of potatoes in maine

SummaryLatent mosaic caused by virus X is harbored more generally than any other virus disease by most of the old and some of the new potato varieties. This disease is harbored by some varieties without producing symptoms, whereas in other varieties it appears as a typical mosaic.Latent mosaic is caused by several strains of virus X, which are distinguished by the severity of the host reaction. In addition to causing more severe foliage symptoms, the stronger virus X strains depress the yield more than the weak strain.It is shown that latent mosaic reduces the yield by 9 to 22 per cent, that the yield is depressed more in some varieties than in others, and that annual losses amounting to millions of bushels result from this disease.Control measures are indicated involving propagation of seed potatoes on isolated fields, protective inoculation with a weak strain of the virus and the development of varieties immune from latent mosaic.

Potato cull piles as a source of late-blight infection

foliage, and this injury may reduce yields in fields where there is no blight or in those in which the disease is not severe. In Florida, also, new potato varieties, such as the Sebago, even though mildly resistant to late blight, succumb to the disease and can not be grown profitably during blight years unless sprayed or dusted regularly. Late blight can be controlled fairly satisfactorily most seasons, even when the disease is severe, if the potatoes are sprayed or dusted regularly with copper sprays or dusts. Poor control of the disease can be traced to several factors such as ( I ) using seed containing many blighted tubers, (2) ideal conditions for the development of the disease in some seasons, (3) failure of some potato growers to realize the seriousnes~ of the disease and to apply fungicides soon enough and follow a regular dusting or spraying program while the disease is spreading, (4) poor coverage of potato foliage with fungicides due to inefficient operation of sprayers and dusters, or to the use of faulty machines, and (5) prolonged rainy periods during which the organism is disseminated and becomes very destructive in fields which become so boggy that spraying and dusting equipment can not be pulled through them making it necessary to abandon the regular dusting or spraying schedules.

Breeding for resistance to late blight in the potato

Twelve years ago the United States Department of Agriculture, in cooperation with the Maine Agricultural Experiment Station, began a program for breeding potato varieties with high )field, good market qualities, and good cooking qualities, combined with resistance to late blight (Phytophthora infestans (Mont.) DBy.). During this time several reports of progress have been published. In addition, the Sebago variety, which is moderately resistant in both vines and tubers, has been increased and distributed to growers. How well this variety has been received is shown by the fact that in 1944 1,8Ol,596 bushels of certified seed were produced in I I states. About 85 per cent of this amount was produced in Maine, but varying amounts were reported also from Maryland, Michigan, Minnesota, New Jersey, New York, North Dakota, Pennsylvania, Vermont, Washington, and Wisconsin. The present paper is an attempt to bring the results of the blight-resistant phase of potato breeding up-to-date and to discuss some of the newer family lines, selections from which show much higher degrees of resistance than Sebago.

Studies on the control of potato bacterial seed-piece decay and blackleg with antibiotics

ConclusionsTreating cut seed potatoes in solutions of streptomycin sulfate or of streptomycin sulfate combined with terramycin hydrochloride is an effective method for reducing the losses from blackleg and from seed-piece decay or missing hills caused byE. atroseptica andP. fluorescens.

The control of potato late blight tuber rot

PUBLISHED BY THE POTATO ASSOCIATION OF AMERICA N E W BRUNSWICK, N. J. O F F I C E R S AND ~XECUTIV~ C 0 ~ ~ E. B. TUSSING, P r e s i d e n t . . . . . . . . . . . . . . . . Ohio State University, Columbus, Ohio MArx KOEHNKF~ Vice-President..Nebr. Certified Potato Growers, Alliance, Nebr. W. H. MARTIN, Sec.-Treas., Editor..Agr. Exp. Sta., New Brunswick, New Jersey F_, L. NEwmcl~ . . . . . . . . . . . . . . . . . . . . . . . Department of Agriculture, Augusta, Maine W. N. KEENAI~ . . . . . . . . . . . . . . . . . . . . . . Department of Agriculture, Ottawa, Canada F. J. SrEWNSON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . U. S. D. A., Beltsville, Maryland C. D. GAINES . . . . . . . . . . . . . . . . . . Department of Agriculture, Olympia, Washington A. H. EDDmS . . . . . . . . . Florida Agricultural Experiment Station, Hastings, Florida

Saco: A new late-maturing variety of potato, immune from common race of the late blight fungus, highly resistant to if not immune from net necrosis, and immune from mild and latent mosaics

SummarySaco (U.S.D.A. B 606-67) is a late-maturing high-yielding variety. The tubers of Saco are predominantly short and round with a tendency to produce off-types. After grading out the poorly shaped potatoes the net yield of marketable tubers is often higher than that produced by standard varieties. Saco, as grown in Maine, produces tubers as high in dry matter as the best standard varieties. Its tubers accumulate reducing sugars at a low rate at 40° F. High-quality chips and french fries were made from them without reconditioning after about 4 months in storage at 45° F.Saco is susceptible to verticillium wilt but yields comparatively high in soil infested with the causal fungus. It is immune from the common race of the late blight fungus, highly resistant to if not immune from net necrosis, immune from mild mosaic, and immune from latent mosaic. It is the first variety released in the United States immune from latent mosaic. Its high-yielding ability and disease resistance should make it one of the cheapest varieties to grow, and its high dry matter content should make is satisfactory for table use or processing.

Effects of antibiotic and fungicidal treatments on wound periderm formation, plant emergence, and yields produced by cut seed potatoes.

SummaryTreatment of freshly cut seed potatoes in a 100 ppm Agri-mycin solution reduced the amount of bacterial seed-piece decay but it also reduced the rate and extent to which the wound protective layer was formed. The treatment caused abnormality in the shape of the cells of the newly formed periderm layer and the adjacent parenchyma tissue. Combining the fungicide captan with Agri-mycin in the treating solution did not eliminate the effect of the antibiotic on the formation of a woundperiderm layer in cut seed potatoes. The Agri-mycin-captan treatment increased the susceptibility of the seed pieces to surface growth by molds and to decay byFusarium spp. The antibiotic-fungicidal treatment, however, did not reduce plant emergence or size of crop produced in the experiments conducted in Maine in 1958.

The Teton potato: A new variety resistant to ring rot

SummaryTeton has shown a high degree of resistance to ring rot over a period of years in Wyoming and Maine. It is not immune from the disease. It produced satisfactory yields in tests in both Wyoming and Maine. In cooking tests made in cooperation with the Home Economics Department of Wyoming Experiment Station, Laramie, Teton was superior to Triumph and Irish Cobbler when baked. When boiled, Teton was superior to Triumph but slightly inferior to Irish Cobbler. Tests for dry-matter content in Maine showed Teton to be lower in this respect than Green Mountain and Mohawk but high enough to indicate good cooking quality.If ordinary sanitary precautions are adhered to, Teton should be valuable in districts where ring rot is a serious menace to potato production.

Bacterial wilt and soft-rot of the potato

Bacterial wilt and soft-rot of the potato may become a very serious problem. Certification officials, plant pathologists, and growers should take measures to prevent it from spreading and causing large losses. This paper is intended to help such persons in detecting and controlling this new potato malady. Bacterial wilt and soft rot was found in Canada in 1931 ( I ) and in Maine in 1932 (2). Since then the disease has been reported from Pennsylvania 1, Florida (4) , and Wyoming (5) . Correspondence and potato specimens received by the writer indicate that this disease is present in other states as well. A bacterial tuber ring-rot was described in Germany in 1913 by

Merrimack: A new variety of potato resistant to late blight and ring rot and adapted to New Hampshire

SummaryMerrimack is a variety of potato bred by the United States Department of Agriculture and tested in New Hampshire. Maine, and elsewhere as part of the work of the National Potato-Breeding Program. Merrimack competed favorably with standard varieties in New Hampshire. It produced satisfactory yields of potatoes, with a relatively high dry-matter content from which excellent chips and french fries were made.In the Maine tests it did not yield as well as some of the standard varieties but in tests it was found to be highly resistant to, if not immune from, the common race of the late blight fungus in both vines and tubers. It is moderately resistant also to early blight, and was apparently fieldimmune from virus A and highly resistant to net necrosis. Its vines are very susceptible to leaf roll virus. Merrimack is not only highly resistant to ring rot but is the first variety released that is highly resistant to both late blight and ring rot. Its multiple-disease resistance should make it valuable, especially to growers who find it difficult to control late blight and ring rot in standard varieties.