United States fruit crops

In the United States, these crops include wheat, com, soybeans, grasses, cotton, and a wide variety of fruits and vegetables. Leading crops in other coimtries vary widely, depending on the nature of the local soil, geography, and growing season. 

Obviously, pollinators are indispensable to most flowering plants. What is more easily overlooked is that they are critical to our own survival as well. Agriculture feeds the world, and about two-thirds of the world s crops require visits by animal pollinators to set fruit and seed. Various kinds of bees pollinate 60 percent of these crop plants, honey bees being the most important single species in this regard. In the United States alone, their contribution to crop pollination is worth billions of dollars every year. 

Although simazine was the first triazine to be developed and marketed in corn as well as other crops, the more versatile atrazine quickly became the standard herbicide in corn. Simazine, however, has remained very valuable and is important on forage crops, ornamentals, turf, and several other vegetable, fruit and nut crops, including almond, apple, artichoke, avocado, berries, cherry, citrus, grape, hazelnut, peach, and walnut. There also remains a strong demand for simazine use in corn in some areas based on specific weed pressure. Simazine is manufactured and sold by several companies today in more than 25 countries around the world, with Brazil, the United States, Australia, and Japan ranked as the top four. 

Yield loss in fruit and nut crops caused by weeds that are not adequately controlled by available herbicides or weed management techniques was estimated at 450 million annually in the United States (Chandler et al., 1984). 

Deciduous fruit plants that lose their leaves each winter and become dormant include apple, pear, peach, prune, plum, cherry, apricot, fig, grape, bramble, and bush fruits. The deciduous nut crops include principally walnut, almond, pecan, pistachio, and hazelnut (filbert). Nearly 11 million tons (10 million metric tons) of fruit come from deciduous plants grown in 43 states in the United States. In 1998 in California alone, 8.9 million tons (8.1 metric tons) of fruits and nuts were harvested (Olds, 1998). Strawberry and pineapple, though not deciduous fruits, are included in this chapter because of triazine use on fruit crops. The major growing areas for the United States are shown in Table 17.1, and these same crops are grown in many countries throughout the world. 

Table 17.1 Examples of fruit crops grown in different regions of the United States...

Trees vary in their response to simazine (Lange et al, 1969a). Walnut was the most tolerant of all deciduous fruit or nut tree species in this study, which used rates that exceeded the label use rates. Several scientists have reported increased nut quality (Larson and Ries, 1960 Neilsen and Hogue, 1992), tree growth, and leaf nitrogen from applications of simazine (Tweedy and Ries, 1966 Neilsen and Hogue, 1992). The extent of use and crops treated with simazine in California and in crops in the United States are covered in Tables 17.2 and 17.3. 

Table 32.5 Adoption of IPM practices in 2000 in field crops, vegetables, and fruit and nuts in the United States as adopted from USDA-NASS 2001 (a partial listing)...

Fungicides are essential for the production of high quality deciduous tree fruit crops in the humid eastern United States. On apples, ten to fifteen applications of one to three fungicides are used each season. Although the frequent application of fungicides is costly, dependence upon chemicals for the production of disease-free fruit crops will continue for the foreseeable future. 

Fungicides are used on stone fruit crops in the eastern United States to control brown rot blossom blight and fruit rot (Monilinia fructi-cola), cherry leaf spot (Coccomyces hiemalis), powdery mildews (Sphaerotheca pannosa and Podosphaera oxyacanthae), and scab (Clado-sporium carpophilium). In the northeastern states about six applications are applied per season while in the southeastern states up to ten applications are applied. 

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