Citrus control

CgH,3BrN202. A soil-acting herbicide. White crystalline solid, m.p. 158-159" C. It is a non-selective inhibitor of photosynthesis used for weed control In citrus and cane fruit plantations. It is relatively non-toxic to animal life. 

D. A. Kimball, Citrus Processing Quality Control and Technology, Van Nostrand Reiohold, New York, 1991. 

Tinplate that meets the rigid specifications imposed by these controls is sometimes supplied as special quality material and undoubtedly can give improved shelf-life, particularly with citrus fruits. The A.T.C. value has probably more effect on shelf-life determined by hydrogen swell than any other factor. 

Frozen Foods. Corrosion caused by the reaction of foods with aluminum containers is unusual if the products are handled and stored at 0°F or lower. However, the inevitable bad handling of frozen foods during commercial distribution causes undesirable thawing. In this condition, not only does the food deteriorate, but it can also attack the container. Such unwanted reactions can be effectively controlled by using coated aluminum containers. Since aluminum is highly compatible with frozen fruits and citrus juices, it has been used extensively as a liner for fiberboard composite cans, as complete aluminum cans, or as ends in combination with steel can bodies in the frozen food industry. 

Biological and Natural Controls. Parasites and predators are effective in limiting the numbers of pest Insects and plant pathogens both in nature and for crops (35). This basic fact led to the development of biological controls. For example, the vedalia beetle, which was Introduced for control of cottony cushion scale on citrus in California, has provided continuous effective control of this pest for many decades. Worldwide only approximately 1% of the pests have been effectively controlled by Introduced biological control agents (43). 

A method has been reported for the quantification of five fungicides (shown in Figure 5.39) used to control post-harvest decay in citrus fruits to ensure that unacceptable levels of these are not present in fruit entering the food chain [26]. A survey of the literature showed that previously [27] APCl and electrospray ionization (ESI) had been compared for the analysis of ten pesticides, including two of the five of interest, i.e. carbendazim and thiabendazole, and since it was found that APCl was more sensitive for some of these and had direct flow rate compatibility with the HPLC system being used, APCl was chosen as the basis for method development. 

Figure 5,39 Structures of various fungicides used in the control of post-harvest decay in citrus fruits. Reprinted from J. Chrormtogr., A, 912, Fernandez, M., Rodriguez, R., Pico, Y. and Manes, J., Liquid chromatographic-mass spectrometric determination of post-harvest fungicides in citrus fruits , 301-310, Copyright (2001), with permission from Elsevier Science.

Carotenoids and prostate cancer — Numerous epidemiological studies including prospective cohort and case-control studies have demonstrated the protective roles of lycopene, tomatoes, and tomato-derived products on prostate cancer risk other carotenoids showed no effects. " In two studies based on correlations between plasma levels or dietary intake of various carotenoids and prostate cancer risk, lycopene appeared inversely associated with prostate cancer but no association was reported for a-carotene, P-carotene, lutein, zeaxanthin, or p-cryptoxanthin. - Nevertheless, a protective role of all these carotenoids (provided by tomatoes, pumpkin, spinach, watermelon, and citrus fruits) against prostate cancer was recently reported by Jian et al. ... 

The source materials were commercial pectins apple A30 and citrus pectin C73 kindly supplied by Unipectine (France) and Copenhagen Pectin Factory (Denmark) respectively. Polygalacturonic acid samples (named SR) were obtained by acid hydrolysis of a fully de-esterified citrus pectin as previously described [24]. Citrus pectins with different degree of esterification (DE) were obtained by controlled acid de-esterification [8]. 

Fig. 4. Ethylene production by MG pericarp discs treated with 50 /rg (uronic acid equivalents) of partially purified G7 citrus oligomers (a) or 30 rg of individual B fruit oligomers purified by HPLC. Water was used for the control. Peak numbers correspond to those shown in Fig. 2. Bars indicate SEs for the means of measurements of 8 discs/treatment.

Activation studies were conducted at pH 7.5 at 30°C in 20 mL of 0.5% high methoxyl citrus pectin (Citrus Colloids, Hereford, U.K.). Final cation concentration in PE extracts used for activation studies was less than 2 mM as measured by potentiometry. Controls were conducted to correct for non-enzymic alkali consumption, with no polyamine/no PE and polyamine added/no PE. PE activity was normalized as a percentage of activity with no cation addition. 

Ultrafiltration of heterogenous colloidal suspensions such as citrus juice is complex and many factors other than molecular weight contribute to fouling and permeation. For example, low MW aroma compounds were unevenly distributed in the permeate and retentate in UF in 500 kd MWCO system (10). The authors observed that the 500 kd MWCO UF removed all suspended solids, including pectin and PE. If PE is complexed to pectate in an inactive complex, then it is conceivable that release of PE from pectin with cations will enhance permeation in UF. At optimum salt concentration, less PE activation was observed at lower pH values than at higher pH (15). In juice systems, it is difficult to separate the effect of juice particulates on PE activity. Model studies with PE extracts allows UF in the absence of large or insoluble particulates and control of composition of the ultrafilter. In... 

Reed, J.B., Hendrix, C M. Jr., Hendrix, D.L. 1986. In Quality Control Manual for Citrus Processing Plants. Volume I. INTERCIT, Inc. Safety Harbor, FL. 

An insect growth regulator, used to control early instar larvae of Homoptera, Lepidoptera, and Coleoptera in citrus, cotton, and vines and fruiting vegetables The residue of concern is for the parent, fenoxycarb, only... 

One of the best illustrations of high specificity is di(4-chlorophenoxy) methane (Neo-tran), which has been used for some time commercially in the field, principally for the control of the citrus red mite. So far there has been no indication of undesirable effect upon pollinating insects or on desirable predators or parasites. 

Mirex and chlordecone are no longer made or used in the United States. Mirex and chlordecone were most commonly used in the 1960s and 1970s. Mirex was used as a pesticide to control fire ants mostly in the southeastern part of the United States. It was also used extensively as a flame retardant additive under the trade name Dechlorane in plastics, rubber, paint, paper, and electrical goods from 1959 to 1972 because it does burn easily. Chlordecone was used to control insects that attacked bananas, citrus trees with no fruits, tobacco, and ornamental shrubs. It was also used in household products such as ant and roach traps. Chlordecone is also known by its trade name Kepone . All registered products containing mirex and chlordecone were canceled in the United States between 1977 and 1978. 

Red scale is a problem in many of the drier banana growing areas. The damage is occasioned by injury to leaves, but the most noticeable damage is in the yellow spotting of the green fruit where the scale has been attached. So far the only control for red scale has been oil emulsion sprays similar to those used in the citrus industry. Highly toxic insecticides, such as used on citrus, cannot be used on bananas because the fruit is harvested almost every day. 

Pest Control in Citrus Production in Tropical and Subtropical America... 

The time-honored method of controlling insect-borne virus diseases is by breeding resistant varieties. This has been practical in annual crops, but is hopelessly slow in tree crops, where it may take 20 years or more to test a new variety. What is needed desperately is some sort of treatment which will control the virus, probably a systemic treatment, as the virus works within the plant cells. This is not a new idea and work has been done along this line by many workers. A sense of urgency is inevitable, however, when 500 to 600 acres of citrus can be wiped out completely in 3 to 5 years time, followed by an expensive replanting job and a wait of 5 to 6 years to get back into production. This is the outstanding problem at the present time and may need years to answer. 

The nematode problem in citrus is very different from the problem in vegetables and other annuals, where the soil can be fumigated between crops. The final solution of this problem will require either a resistant rootstock or a treatment which will tip the balance in favor of the tree. This latter might be either a systemic which will move downward in the tree and make the roots either poisonous or distasteful to nematodes or a soil treatment which will penetrate to great depths and destroy the nematodes without seriously injuring the trees. Either type of control is a big order. Standard known rootstocks are all attacked and an entirely new rootstock might require 25 years to test thoroughly, while in the chemical field there is no precedent in other crops. 

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