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Air Pollutants, especially photo- chemical smog and fluorides, are known to cause major damage to agricultural crops. Commercial production of leafy vegetables has been seriously hampered in the Los Angeles Basin because of oxidant lesions which reduce their quality or render them totally unsalable. High levels of fluorides can cause visible damage to crops; where no leaf lesions can be seen, careful environmentally controlled studies are required to determine the extent of injury attributable to fluorides.

Previous studies of mechanical clipping, or topping of canning tomato plants grown for mechanical harvesting showed that this technique could be used satisfactorily to spread harvest dates and obtain plant uniformity. Since a onceover or single harvest method is also being used in the mechanical harvesting of pickling cucumbers, the purpose of these tests was to determine whether a similar delayed-maturity effect might occur that would aid growers in scheduling cucumber plantings for mechanical harvesting. Field trials were conducted at Davis during a three-year period (1966-68) and in the greenhouse during the winter of 1967. The monoecious pickling cucumber variety SMR-58 was used in all experiments. In addition to the SMR-58 variety, the gynoecious hybrid Piccadilly was used in the 1967 and 1968 field tests and in the greenhouse study. The field plot work of 1967 with the variety SMR-58 represents the results of these findings and is reported here. The plots were seeded May 29 in double rows on 40-inch beds. Germination was on June 3 and plants were thinned June 8 leaving three plants per clump, 6 inches apart.

A study of boron removal by flooding and sprinkling during one winter's leaching program indicated boron was leachable and that sprinkling and flood irrigation were equally as efficient at removing boron. The 25 inches of water applied by flooding removed 61 per cent of the boron from the 4-ft rooting depth sampled. Fifty-two per cent of the boron was removed by sprinkling.

Considerable Variation has been shown to exist among plants of commercial asparagus. The greatest differences have been found between staminate and pistillate plants, but variability within the sexes has also been reported. This study was undertaken to determine the amount of variation within five California lines grown in southern California, and to identify superior plants for use as breeding and planting stock.

Agriculture still suffers huge financial losses each year from air pollution, but is now itself being examined with increasing vigilance as a source of pollution. Controlled fire has always been used by farmers for the preservation of food, for the destruction of pests and diseases, and for the disposal of wastes. Disposal of wastes—including straw, stubble, tree prunings, dead trees, and brush clearing on rangeland—produces smoke, odors, dust and air-borne particulate matter that is increasingly objectionable (but not necessarily harmful) to city dwellers as they continue to move out into rural areas. On the other hand, people-produced damage to farm crops from photo-chemical pollutants (resulting mostly from automobile exhaust) often occurs in the absence of analytical instruments that show first signs of air pollution. It is therefore important that there be continued surveillance of air pollution damage to agriculture, as well as measurement of amount and effects of agriculturally-produced pollution. This article discusses legislation, regulations and control aspects of the air pollution problem on a statewide basis, and offers a course of action for the future.

Two derivatives of fluorene-9-carboxylic acid (termed morphactins because they produce morphological changes and striking suppression of growth in plant species) were tested on seeded Vitis vinifera, Muscat of Alexandria; and seedless Thompson Seedless, and Black Corinth grapes. Berry abscission was induced when the compounds were applied at the fruit-set stage or two weeks later. When morphactins were applied near maturity, no berry drop occurred although the strength of berry attachment was reduced. An auxin (4-CPA) counteracted the morphactin response, indicating that the response may involve auxin metabolism. These chemicals are not registered for use in the U.S. at this time except by researchers on an experimental basis.

The Proper Planting Depth of wheat seed is particularly important for good seedling emergence and stand establishment when short-statured varieties are grown. Research in progress at U.C., Davis indicates that the recommended planting depth of 1½ to 2 inches should be followed closely when currently popular varieties such as Pitic 62, Lerma Rojo 64, Sonora 64, and other short-statured wheats are used. The length of the coleoptile (the protective sheath which surrounds the first foliage leaves prior to emergence) is the reason, since it often is only 50 to 75 per cent as long as that found in Ramona 50 and other taller varieties. Certain wheat strains— if planted deeper than 2 inches—may never develop a coleoptile long enough for emergence.

Two hybrid sugar beet varieties with moderate resistance to virus yellows have been released to California growers. The varieties designated US H9A and US H9B are both monogerm and were developed at the U. S. Agricultural Research Station, Salinas. The new varieties perform best in those areas of the State in which damage from yellows is severe, but they also perform well under yellows-free conditions. In 17 tests under conditions of moderate to severe yellows, US H9A produced 22 per cent more sugar than did the widely grown US H7 variety. In 11 tests, US H9B produced a 27 per cent higher yield of sugar than did US H7. Both varieties averaged about 0.3 of a percentage point higher in sucrose than did US H7. Seed has been produced by the sugar companies and is now available for wide scale planting.