A seed transfer certificate is required anytime untagged seed moves, no matter where it is going outside of the county in which the seed is residing, such as from the field to conditioner, from conditioner to conditioner, from California to Minnesota, or from California to Chile. The three types of seed transfer certificates are inter-county, intra-county, and inter-agency . The primary market for sunflower seed is Eastern Europe , where more than 50 million acres of sunflowers are grown for cooking oil. Seed is also marketed and sent to the U.S. Midwest, where about 1.7 million acres of sunflowers are grown primarily for cooking oil, but also for confectionary seed, with the Dakotas being the top sunflower producer in the United States. Other hybrid sunflower seed producers include Turkey, Chile, and Argentina.Broad leaf Weeds A wide range of broad leaf weeds infest small grains . The more common weeds are mustards , wild radish , London rocket , shepherd’s purse , coast fiddleneck , annual sowthistle , prickly lettuce , burning nettle , pineapple weed , miner’s lettuce , common chickweed , field bindweed , swamp smart weed , common lambs quarters , and yellow starthistle . Broad leaf weeds vary in their ability to compete with small grains. For example, an average of 1 wild radish plant per square foot , when established at the same time a wheat crop emerges, can reduce yield by as much as 66 percent by completely over topping the wheat canopy and competing for light. Low-growing weeds such as common chickweed, henbit , growing racks and miner’s lettuce are generally less competitive, but even high populations of common chickweed can smother small plants, reduce yield, and remove soil nutrients and moisture. Poor weed management also causes weed problems in succeeding crops.

Grasses Grass weeds are difficult to control in small grains because they mimic the growing cycle and growth habit of the crop. Many grass weeds germinate at the same time as small grains and mature slightly before or at the same time as the crop, assuring an ample supply of seed for next year’s weed crop. These weeds compete for light and space and also remove soil moisture and nutrients needed for crop growth. Winter annual grassy weeds in California’s small grains include wild oat , Italian, or annual, ryegrass , ripgut brome and downy brome , hare barley , rabbits foot grass , and hood canary grass and little seed canary grass . Wild oat emerges throughout the cool season from autumn through spring. In small grains it causes lodging, slows harvest, clogs harvester screens, and lowers yields. An average of 7 wild oat plants per square foot can reduce wheat yields by 3,000 pounds per acre in a crop with a yield potential of 6,000 pounds per acre . Barley, because of its more competitive early growth, is less affected by wild oat than is wheat. In one study a wild oat density averaging 14 plants per square foot reduced barley yield by 27 percent and wheat yield by 39 percent . Ripgut brome is a particular problem in rainfed production areas. The weed reduces yield by competing with the crop, and its seed can contaminate the grain and reduce its marketability. Italian ryegrass is a major weed in the central and northern valleys of California. Infestations of hood and little seed canary grass can reduce yields by more than 50 percent. Hood canary grass occurs in the central region and coast rainfed production areas, while little seed canary grass is most prevalent in the Imperial Valley and Southern California. Canary grass is a prolific seed producer, and populations of canary grass in fields continuously cropped to small grains often exceed 100 plants per square foot . Hare barley and rabbits foot grass are common in the southern part of the state, although hare barley is sporadically found elsewhere in California.An integrated weed management system combines crop rotation, fertilization, irrigation, tillage, herbicide applications, and high plant populations to help control weeds.

Field sanitation is a prerequisite for weed control. Planting and tillage implements should be free of weed seeds and other plant propagules to avoid spreading weeds from field to field. Field perimeters should be kept free of weeds because they serve as a reservoir for seed to infest the field. A properly prepared seedbed can increase yield and reduce weed pressure . Plant high-quality, vigorous, weed-free certified seed. Using non-certified seed risks the introduction of new weed infestations. The sowing date can influence weed competition. Late sowing produces shorter small grain plants that have fewer tillers and are less competitive with weeds. Lower seeding rates also can intensify weed pressure. Studies in the Sacramento–San Joaquin Delta have shown that higher seeding rates are very effective at reducing competition by swamp smart weed, johnson grass, mustard, wild oat, canary grass, and common chickweed. Row spacing should be as narrow as feasible to promote early development of a solid, competitive crop canopy. Mulch planting can give a small grain crop a head start over weeds. In mulch planting, a shallow cultivation is done following rainfall or irrigation, when weed seeds germinate before planting. The crop seed is then sown into moist soil below the mulch layer of dry soil that resulted from the cultivation. Because the crop seed is placed into moist soil, it germinates quickly, ahead of weeds. Fertilization is essential to maximize small grain vigor and health and is an excellent weed suppression practice . Starter fertilizer may be required in some areas. Place starter fertilizer near the seed to provide early availability to the crop, not to weeds. Broadcast-applied starter fertilizer enhances weed growth, especially for wild oat and canary grass; broadcast applications are less efficient and should be avoided. Irrigation and proper drainage keep small grains in a vigorous growing condition for maximum competition with weeds .

In areas where flooding and high water tables occur, small grains should be sown on 30- to 60-inch raised beds. For rainfed production systems, growing weed vertically fields can be fallowed every other year to prevent weed seed buildup and to conserve moisture for maximum small grain growth. Weeds should not be permitted to produce seed during the fallow period. Tillage operations before planting should be delayed until the first fall rains germinate the weed seeds so that tillage can kill the first flush of weeds before sowing. Weeds may also be treated with an herbicide during the fallow period . Rotating small grain crops with other crops reduces infestations of johnsongrass, wild oat, Italian ryegrass, and other weeds that are important in small grains . Crop rotation allows weed populations to be reduced chemically, mechanically, and physically in the alternate crop. Growing different crops at different times of the year helps break the reproduction cycle of some problem weeds. Small grains are often grown so that weeds important in higher-value crops can be controlled. For example, small grains grown in rotation with vegetable crops allow post emergent broad leaf herbicides to be used to control nightshades and sowthistle, major problems in vegetable crops.Good cultural practices help reduce weed competition, but an integrated approach involving these measures as well as herbicide applications is often needed for complete weed control. An integrated approach reduces weed seed production and aids weed control in succeeding crops. The effectiveness of a chemical weed control program depends on the weed species present, application timing, thoroughness of spray application, environmental conditions at the time of application, herbicide use rate and spray volume, and crop management after the application is made. For example,weeds may again cause problems if late-winter rains stimulate additional weed seed germination after a herbicide application is made. Also, drought-stressed weeds are very difficult to control with post emergent herbicides, especially if they are beyond the seedling stage. Susceptibility of problem weeds to available herbicides is given in the susceptibility table in UC IPM Pest Management Guidelines, Small Grains . This table is kept up to date with the latest available herbicides.Only post emergent herbicides, which are applied after the crop has emerged, are used for weed control in small grains. Fall-sown small grains are usually treated between December and mid-March, depending on the sowing date and growing conditions. Spring-sown small grains in the inter mountain area of northern California are treated between April and June. Several post emergent herbicides are registered for use in small grains. Phenoxy herbicides, including 2,4-D and MCPA, are commonly used in small grains alone or in combinations. Dicamba, another hormonal-type herbicide, is often included in the phenoxy herbicide group because of its similar mode of action.

These herbicides are most effective when applied to small, succulent weeds. Small grains vary in their sensitivity to these herbicides; for example, oat is more tolerant to MCPA than to 2,4-D. Ester and amine formulations of 2,4-D and MCPA amine formulations control most broad leaf weed species encountered in small grains. The ester form is usually more effective than the amine form. However, ester use is not permitted in most counties, or applications are limited to certain times of the year. Figure 1 illustrates the proper application timing of these herbicides. Phenoxy herbicides should be applied after the small grains are well tillered but before they reach the boot stage in order to avoid yield reductions caused by phytotoxicity . Late applications are sometimes ineffective because the crop canopy shields the weeds, preventing herbicide contact. Dense weed populations require a more thorough application with a greater spray volume to ensure contact between the herbicide and weeds. The use of aircraft often facilitates timely herbicide application, but care must be taken to make applications at the appropriate time to avoid injury to adjacent crops from drift or volatilization. MCPA does not control large weeds as well as 2,4-D amine and 2,4-D ester herbicides, but it has greater crop safety, especially when applied to small grains in early growth stages. Dicamba is effective for broad leaf weed control; however, small grains are generally more sensitive to it than they are to 2,4-D. Dicamba is safter when applied at early growth stages . It cannot be used on fall-sown barley. Dicamba controls small plants of common chickweed and coast fiddleneck, which are not controlled by 2,4-D or MCPA. It usually is combined with bromoxynil and MCPA. When applied early, this combination is very effective and increases the weed spectrum controlled compared with either of the herbicides used alone. Bromoxynil , a contact herbicide, is effective on young seedling weeds with no more than 2 to 4 leaves. It is less effective on older weeds and must be tankmixed with other herbicides, for example, when larger mustards are present. Bromoxynil is not translocated from the site of absorption like the phenoxy herbicides. Therefore, higher-volume application and thorough coverage is more important with bromoxynil than with phenoxy herbicides. An advantage of bromoxynil is that it controls the toxic weed coast fiddleneck when applied at early growth stages of the weed; phenoxy herbicides often fail to control coast fiddleneck. Bromoxynil is also recommended in areas with phenoxy-sensitive crops such as grapes, cotton, and tree crops. Chlorsulfuron is registered for use on wheat in a wheat-fallow rotation. It is a sulfonyl urea herbicide with a very low application rate. It is not widely used in California because it has a long soil life , which prevents its use in areas where many different crops are grown. This herbicide controls most broad leaf weeds, including coast fiddleneck and common chickweed. It should be applied to small weeds when the small grain crop is in the 2 to 3 leaf stage to boot stage and should not be used on soils with pH above 7.5. Clopyralid , a picolinic acid, is registered for use on wheat, barley, and oats. It translocates systemically through weeds, similar to phenoxy herbicides. It has a longer soil persistence than phenoxy herbicides, which limits planting of some broad leaf crops before 12 to 18 months after application. It is effective on a different spectrum of weeds than 2,4-D, MCPA, or dicamba.