Wm. G. Hoyman

Observations on the use of potato vine killers in the red river valley of North Dakota

Conclusions1.Nine vine killers were applied as sprays or dusts to potatoes at Grafton, North Dakota, at various times from the Ist of August to the 6th of September, 1946.2.In the absence of dew, the dusts were not effective.3.Weed Killer A at 37.5 or 50 lbs. per 100 gal. of water was the most rapid killer.4.The effectiveness of Dowspray 66 Improved was increased by the addition of aluminum sulphate.5.The addition of ammonium sulphate to Sinox General and ammonium dinitro butyl phenol increased the rapidity of kill.6.The discoloration found in and near the vascular (conductive) tissue of tubers harvested from treated vines may or may not be a direct effect of the vine-killing chemicals.7.Tubers harvested from untreated, cut vines showed the same type of discoloration present in tubers harvested from vines treated with vine killers.8.The amount of discoloration was positively correlated with the rapidity of kill and was less when the applications were made later in the season.

Effect of certain systemic insecticides on the incidence of verticillium wilt and the yield of Russet Burbank potato

SummaryDi-Syston granules or spray, and Systox spray, delayed Verticillium wilt vine symptoms on Russet Burbank potato, and significantly increased the total yield at the 1% level. A similar yeild response was obtained from Bayer 37289 granules.In most instances, the highest-yielding treatments produced the greater number of tubers.The treatments yielding the most had the highest average tuber weights. An exception to this was Phosphamidon 8 spray.The treatments resulted in no definite trends with respect to percentage of U.S. No. 1 tubers and specific gravity.It appears that the increased yields, as a result of certain systemic insecticides, were due to factors other than foliar insect control. SPECIAL NOTE:The systemic insecticides used in this experiment have not been registered for use as fungicides. Unless and until any one of these substances is registered for use as a fungicide for the control of the fungus causing Verticillium wilt, it must not be recommended for that purpose.

Red Pontiac vine and tuber yields as affected by virus X

SummaryRed Pontiac tubers from 40 different midwestern sources were indexed to determine what strain or strains of virus X were present.A moderate strain of the virus was found to be commonly present.No distinct X-virus symptoms were observed in greenhouse-grown plants except for the periodic appearance of a faint leaf mottle, most easily detected on cloudy days.When grown outdoors, the leaves of Red Pontiac plants infected with the moderate strain had a slight upward, lateral roll and were slightly wrinkled. The infected leaves were not as dark green in color as virus-free leaves.The mean replicate weight of the X-free vines was 25.43 pounds compared to 17.41 for the infected plants; a highly significant difference of 31.54%.The mean replicate weight of the X-free tubers was 37.02 pounds compared to 28.93 for those infected with the virus. The difference of 8.09 pounds was highly significant and represented a 21.85% reduction in total yield.

Reaction ofSolanum tuberosum andSolanum species toMeloidogyne hapla

The reactions of 218 clones ofSolanum tuberosum and 238 accessions of 55 tuber-bearingSolanum species toMeloidogyne hapla were determined by planting them in soil naturally infested withM. hapla and the microsclerotial form ofVerticillium alboatrum. Degree of root galling was rated from none (0) to severe (5). Incidence of root galling on clones was slight as evidenced by ratings of 0, 0.5 and 1.0 for 38, 32 and 18 percent of them, respectively. As incidence of root galling increased there was a tendency for percentage of galled tubers and internal tuber infection byM. hapla to increase. Of many family progenies ofS. tuberosum tested, those from family B7147 (Penobscot x W39-1) were the most resistant toM. hapla. Incidence ofM. hapla root galls andVerticillium alboatrum wilt symptoms onS. tuberosum clones indicated there was no apparent interaction between these two pathogens. Eighty-one percent of the 238 accessions remained free from root galls.Solanum species free from root galls and represented by three or more accessions werebrachycarpum, bulbocastanum, cardiophyllum, hjertingii, hougasii, infundibuliforme, kurtzianum, martinasense, multidissectum, multiinterruptum, papita, sparsipilum, spegazzinii, stoloniferum, tarijense, andvernei. S. microdentum (PI320312) andS. tuberosum ssp.andigena (PI245926) had the most extensive root systems free ofM. hapla galls.

Consequence of planting Norgold Russet seed infected withVerticillium albo-atrum

Norgold Russet seed internally infected withVerticillium albo-atrum and free of external tuber-borne inoculum was planted inVerticillium-infested and noninfested soils to determine if intratuber infection affected production of this very susceptible variety. It had no effect on emergence, growth rate, size of plants, appearance and severity ofVerticillium-wilt symptoms, total yield, percent U.S. No. 1 tubers, or specific gravity.

Norland a new red-skinned potato variety with early maturity and moderate resistance to common scab

SummaryNorland is an early maturing, smooth, shallow-eyed, red-skinned variety with early yielding ability. It has moderate resistance to common scab and is susceptible to infection by the common potato viruses and to the fungus causing late blight. This variety possesses good cooking and chipping qualities and produces a high per cent of U.S. No. 1 tubers.

Relation of water supply to xylem discoloration of potato tubers caused by vine killing

Summary1In order to determine the relation of water supply to vine killing discoloration, Triumph potatoes were grown under the following conditions: 1) with natural rainfall, 2) with natural rainfall plus irrigation, 3) on elevated soil with natural rainfall, and 4) in one year on elevated soil with natural rainfall but with the soil covered with roofing paper.2The treatment producing the most xylem discoloration was elevating the soil and covering it with roofing paper. This was followed by elevating the soil but leaving it uncovered.3The years 1948, 1949 and 1950 each had a deficiency of rainfall during August and with the exception of 1948 the expected tuber discoloration was obtained in the normally-treated rows.4In 1947 the August rainfall was approximately normal and a departure of +2.75 inches occurred during this month in 1951. The expected low percentage of discoloration was found in the normally-treated rows during each of these years.5A low percentage of discoloration occurred in the tubers harvested from the irrigated rows and from the rows where the vines remained until harvest.6In most instances, early vine killing caused the most discoloration.

Temik: A systemic insecticide effective in delaying verticillium wilt of potato

SummaryWhen 15 pounds per acre of 10% granular temik were banded on Russet Burbank potato at planting and the same amount side-dressed 39 days later, the vine symptoms of Verticillium wilt were delayed longer and the yield was increased significantly over plants banded at planting with 30 pounds per acre of GC 6506, NIA 10242 or phorate.More and larger tuber were produced by plants treated with temik.Only 0.29% of the tubers from temik-treated plants had root-knot nematode galls, whereas 64% of the tubers from the nontreated plants had symptoms. There was evidence that GC 6506, NIA 10242 and phorate restricted tuber infestation by this nematode.There was no evidence thatM. hapla had penetrated the skin of gallfee tubers and caused necrosis of the tissue.The specific gravity of tubers from plants that received temik was lower than the average value of Russet Burbank tubers grown in eastern Washington, but the percentage of U. S. No. 1 tubers was representative for this variety. Special note:The systemic insecticides used in this experiment have not been registered for use as fungicides.ResumenCuando qunice libras por acre de 10% temik (granulado) fueron aplicadas como banda a Russet Burbank a tiempo de sembrar, y la misma cantidad 39 dias despues se puso como aplicacion lateral, los sintomas de marchitamiento (Verticillium wilt) fueron mas dilatadas y los rendimientos aumentados significamente mas que en plantas reciviendo (en banda) 30 libras por acre de GC 6506, NIA 10242 o phorate a tiempo de sembrar.Plantas reciviendo temik produjeron papas en mas abundancia y mas grande en tamano.Unicamente 0.29% de las papas producidas por plantas que recivieron temik demonstraron excoriaciones mientras que 64% de las papas producidas por plantas sin temik demonstraron sintomas.Se pudo ver evidencia que GC 6506, NIA 10242 y phorate restrictaron infeccion por este nema.No se pudo ver evidencia queM. hapla habia penetrado la epidermis de las papas sin excoriaciones y que haya causado necrosis de los tejidos.La gravedad especifica de papas originado de plantas que recivieron temik fue menos que valores comunes de Russet Burbank cosechadas en la parte este del estado de Washington, pero el porcentaje de papas de U.S.#1 fue representativo de esta variedad.Los insecticidas mencionados en este expermento no se han registrado para uso como fungicidas.

Effect of disulfoton on tuber nematode galls, verticillium wilt and yield of Russet Burbank potato

Demeton, the first systemic insecticide approved for use on food crops, and several other organophosphorous compounds have been tested for their nematocidal activity. In experiments with the golden (Heterodera rostochiensis Wollenweber) and root-knot nematodes (Meloidogyne sp.), Sasser, Feldmesser and Fassuliotus (19), and Sasser (18) reported that demeton was nematocidal. Jensen and Caveness (14) showed that demeton was effective in controlling Aphdenchoides ~ragariae (Ritzema Bos) Christie, a foliar nematode. Miller and Perry (16) dipped the roots of certain ornamental plants infected with Meloidogyne incognito (Kofoid and White) Chitwood, PratyIenchus coffege (Zimmermann) Filipjev and Stekhoven, and Radopholus similis (Cobb) Thorne into various concentrations o[ two phosphorothioates, 0,0-diethyl 0-p-(methylsulfinyl)phenyl phosphorothioate (Bayer 25141) and 0,0-diethyl 0-2-pyrazinyl phosphorothioate (Zinophos). They found that both were nematocidal. In greenhouse experiments with tomato root knot, Jarnevic and Coffee (13) compared the effectiveness of two phosphorothioates, 0,0-diethyl 0-p(methylsulfinyl)phenyl phosphorothioate and 0,0-dimethyl 0[4-(methylthio)-m-tolyl] pbosphorothioate (Baytex), and one phosphonothioate, 0-ethyl 0-2,4,5-trichlorophenyl ethylphosphonothioate (Bayer 37289), with two nonorganophosphate nematocides: 1,3-dichloropropene, 1,2-dichloropropane (D-D) and 1,2-dibromo-3-chloropropane (Nemagon). They found that the three organophosphates were much more effective than 1,3-dichloropropene, 1,2-dichloropropane but not as nematocidal as 1,2-dibromo3-chloropropane. Helton (10) demonstrated that dimethoate has a therapeutic effect on the root-knot disease of tomato. Both foliar sprays and soil drenches were effective in suppressing the activity of Meloidogyne hapla Chitwood. In field and greenhouse experiments with 0,0-diethyl S-2-(ethylthio)ethy/ phosphorodithioate (Di-Syston) and 0,0-diethyl S(ethylthiomethyl) phosphorodithioate (Thimet), Streu and Heald (20) obtained increased growth of certain woody ornamentals, and they attributed this response to the nematocidal activity of the systemic insecticides against Tylenchorhynchus ctaytoni Steiner and Pratylenchus vulnus Allen and Jones. In a greenhouse experiment, utii:zing Russet Burbank tubers naturaliy infected with M. hapta, Helton (9) dipped cut seed into various concentrations of dimethoate for various lengths of time. The development of root-knot nematode populations in dimethoate-treated plants varied in-

Importance of tuber eye posiion when indexing for the leafroll virus

SummaryEyes were removed from the stem ends, middle position, and bud ends of leafroll-infected Kennebec, Norland, Red Pontiac, F91-2, and seedling potato tubers to determine which position is the most reliable for expressing leafroll symptoms in greenhouse plants grown from them. The bud end was found to be the most satisfactory.