Stem rot severity is influenced by level and time of nitrogen application. Nitrogen levels allowing maximum yield of California varieties should not be exceeded when considering stem rot disease control.

Current California varieties were tested for relative susceptibility to stem rot. Of the early varieties, Earlirose and Earlirose 76 are the most susceptible, with Colusa and S-6 the least susceptible. L-201 was the least susceptible to Rhizoctonia sheath blight, while M-9 was the most susceptible in this year's test.

Station director Morton D. Morse conducts stem rot screening tests in the new Rice Experiment Station greenhouse. Station scientists report that this work urgently needs to be expanded so genetic resistance can be located and incorporated into the variety breeding program.

The potential for transferring tolerance to stem rot from wild species of rice to our cultivated varieties shows promise and should be pursued.

Du-TerŽ again proved to be the most promising fungicide tested for stem rot control. Other chemicals were tested, some will be investigated further.

No difference in efficiency of seed treatment chemicals on smooth- and rough-seeded varieties was detected. New formulations of CaptanŽ were as effective as the older standard formulations for seed treatment.

Methods for determining when a field should be burned for stem rot control have been developed. These will also be useful in management decisions regarding the use of fungicides in event they become a part of the rice culture system for disease control.