Herbicidal sprays, activity

The Role of Surfactants in Modifying the Activity of Herbicidal Sprays... 

Although it is generally conceded that the nature of herbicidal enhancement is closely allied with penetration (16), surfactants could conceivably influence the activity of herbicidal sprays at several sites. These sites could include areas... 

Foy and Smith (4) recently reviewed the role of surfactants in modifying the activity of herbicidal sprays (66 references). These authors studied the adjuvant effects of a surfactant based on nonyl phenol with varying amounts of ethylene oxide appended. Activity was enhanced at an optimum ethylene oxide chain length. This is another way of stating that there is an optimum surfactant HLB for enhancing herbicidal activity on a given species of weed. 

Biocides should not be present in water used for aquaculture. Sources of herbicides and pesticides are mnoff from agricultural land, contamination of the water table, and spray drift from crop-dusting activity. Excessive levels of phosphoms and nitrogen may occur where mnoff from fertilized land enters an aquaculture faciUty either from surface mnoff or groundwater contamination. Trace metal levels should be low as indicated in Tables 4 and 5. 

Uses Dormant ovicidal spray for fruit trees (highly phototoxic and cannot be used successfully on actively growing plants) selective herbicide and insecticide. 

As shown by the structures in Figure 15.9, a bipyridilium compound contains two pyridine rings per molecule. The two important pesticidal compounds of this type are the herbicides diquat and paraquat other members of this class of herbicides include chlormequat, morfamquat, and difenzoquat. Applied directly to plant tissue, these compounds rapidly destroy plant cells and give the plant a frostbitten appearance. However, they bind tenaciously to soil, especially the clay mineral fraction, which results in rapid loss of herbicidal activity so that sprayed fields can be planted within a day or two of herbicide application. 

Diuron was introduced by du Pont in 1954 (Fig. 3). It is one of a series of substituted urea herbicides. Diuron is applied preemergence to crops such as cotton, alfalfa, grapes, fruit and nut crops. Foliar activity is enhanced when a surfactant is added to the spray. 

DSMA is an organic arsenical having contact, postemergence activity. It was first utilized for crab-grass control in turf. It is an effective herbicide in cotton and in citrus trees, but must be used as a directed spray to avoid contact with the crop foliage. 

Interactions between surfactants and herbicides in spray solutions are known to occur (57), and those studied either have no effect or are detrimental to herbicide activity. No definite evidence exists that surfactant-herbicide interactions in solution cause enhanced activity of herbicides. 

The azido derivative 683 (CGA 19255) had herbicidal and even better insecticidal activity. 683 prevented the development of the larvae of the house fly (Musca domestica) it was tested successfully as a poultry feed-through lar-vicide " . 684 (CGA 72622 cyromazine, Larvadex ), a metabolite of 683 23,824 proved to be better suitable as a larvicide " . It inhibited growth of a great variety of Diptera insect larvae (e.g. house fly, yellow fever mosquito, face fly, sheep blowfly, fall army worm). Additionally, 684 was used as anthelmintic . 684 is applied as a food additive for domestic or livestock animals or by spraying it on manure surface. Larvicidal properties of formamido " and formamidino derivatives of 684 have been tested. The bacterial degradation of 684 was investigated . ... 

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