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Evidence from these greenhouse studies indicates an advantage in uniformity of emergence and seedling vigor from sizegraded seed of muskmelon. However, additional research is necessary to properly utilize this relationship of seed size to seedling emergence and vigor under field conditions.

Perennial weeds are an increasingly important problem in California. This may be due in part to the increased use of preemergence herbicides which reduce the competition to perennial weeds from the normally more prevalent, faster growing, annual weed species. In the process we have increased the relative influence of perennial weeds. Perennial weeds are usually deep rooted; and most often regenerate themselves by growing from underground rootstocks (rhizomes and stolons). Preemergence weed killers are usually ineffective against such large underground storage organs because they are designed to kill only newly germinating weed seedlings close to the surface of the soil.

The distribution of organic chemicals in the soil profile after irrigation or rainfall is important because: (1) the effectiveness of a given pesticide applied to the soil is dependent in part upon its position in the soil profile; and (2) persistent organic chemicals can build up in the surface soil if they are strongly adsorbed, or can be leached into the groundwater if they are very mobile.

Volatilization of nitrogen from animal wastes in combined form, principally ammonia, has recently received attention because of the high concentration of large numbers of animals in some production operations. One constituent of animal waste that is a potential pollutant to surface and ground water is combined nitrogen. Small amounts of nitrogen in animal wastes are also apparently volatilized in the form of amines which are ammonia derived compounds. Amines are one group of compounds that contribute to the objectionable odors emanating from confined animal operations.

Early fruit setting of tomatoes in experimental plots at Riverside, California, has been light in recent years. Unfavorable temperatures in late spring are a probable cause, but increasing atmospheric pollutants may also be involved since phytotoxic levels of total oxidants occur frequently in this area.

Anza, a spring wheat variety released by the University of California in 1971, offers growers a new choice for a variety in the medium-to-late maturity range. Named in honor of Don Juan Baptiste de Anza, who led settlers from Sonora, Mexico to California in about 1775, the variety has followed a similar route.