A high moisture level in the top 10 cm of soil at time of cutting of alfalfa increased the incidence of plant mortality and Fusarium wilt in soil infested with Ditylenchus dipsaci and Fusarium oxysporum f. sp. medicaginis in greenhouse and field microplot studies. Ranger alfalfa, susceptible to both D. dipsaci and F. oxysporum f. sp. medicaginis, was less persistent than Moapa 69 (nematode susc...

The potato rot nematode, Ditylenchus destructor Thorne, is reported for the first time in hulls and seeds of peanut. The populations found differed from D. dipsaei and D. myceliophagus in habitat, number of lateral incisures, shape of tail tip, and length of postvulval sac. Infected hulls had brown necrotic tissue at the point of connection with the peg, and a black discoloration appeared first...

Ditylenchus dipsaci showed an affinity, in relation to infection, for the temp at which it had been acclimated. The optimum infective temp was also correlated with field temp when collections were made during different seasons and from climatically different geographical areas. Nematode developmental stage did not influence infectivity.

Commercial peanut cultivars were evaluated for host suitability and sensitivity to Ditylenchus destructor. All cultivars were susceptible. Approximately 94% of the final population were in the pods. Highest Pf occurred at harvest on early maturing cultivars. Damage occurred on four of six cuttivars at Pi = 100/3 liters of soil and all six cultivars at Pi = 1,000. Norden and Selmani were the mos...

After 18 months of storage at -150 C, some larvae of Ditylenchus dipsaci, which had been treated in a 7.5% solution of dimethyl sulphoxide and cooled to -25 C before storage, were still viable on thawing. Some survivors penetrated and developed normally in stems of alfalfa seedlings. Tests showed that active larvae could be frozen directly, thus eliminating the need to use the quiescent stage o...

Meloidogyne hapla, Pratylenchus penetrans, and Helicotylenchus dihystera, reduced the growth of 'Saranac AR alfalfa seedlings when applied at concentrations of 50 nematodes per plant. All except P. penetrans reduced seedling growth when applied at 25 per seedling. M. hapla reduced growth when applied at 12 per seedling. Nematodes interacted with three pseudomonads to produce greater growth redu...

Field population densities of Ditylenchus dipsaci associated with shoot tissue of Phlox subulata were monitored during two consecutive growing seasons and intervening periods of overwintering and plant storage. The population density increased significantly through four peaks during the first growing season, and decreased significantly during storage at 5-7 C or overwintering in the field. Duri...

The population development of Ditylenchus destructor in the roots, pegs, hulls, and seeds of eight peanut (Arachis hypogaea) genotypes was studied in the greenhouse. Although all genotypes tested were good hosts for D. destructor, differences in host suitability were observed. Invasion of the plant parts by Ditylenchus destructor proceeded more slowly in genotypes with long growth periods. Duri...

Methods are described for rearing large quantities of Ditylenchus dipsaci on alfalfa tissues. Nematodes and alfalfa seed were disinfected and nematodes were reared in quantities sufficient to provide a continuous supply of inoculum for our alfalfa-breeding program. Nematodes reproduced best in darkness at 20-25 C. Cultures reached maximum numbers in 3-6 wk.

The effects of abamectin B1, diazinon, and methiocarb insecticides on Aphelenchoides fragariae and Ditylenchus dipsaci in Lamium maculatum, Phlox subulata, Rhododendron indicum, and Begonia x tuberhybrida were determined in a series of greenhouse experiments. Abamectin at 0.005 or 0.011 g a.i./liter (0.3 or 0.6 ml/liter Avid 0.15 EC), diazinon at 0.62 or 1.87 g a.i./liter (2.6 or 7.8 ml/liter K...