Citrus tree

The first pesticide exposure study was reported by Griffiths et al. (1951). Parathion was trapped on respirator filter discs during application to citrus trees. Batchelor and Walker (1954) expanded exposure monitoring to include the estimation of potential dermal exposure using pads attached to workers clothing. Durham and Wolfe (1962), in their classic review of worker exposure methodologies, also provided some experimental validation for the best available methods. 

Question 8.2 Why does Water Protect Citrus Trees from Freezing ... 

Target species Grapes, Almond trees, Alfalfa, Oleander, Citrus trees. 

Target species Lemons, other citrus trees. 

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. 

The latest development in the field of citrus pests involves nematodes. The citrus nematode (Tylenchulus semipenetrans Cobb) has been known for many years in California, Florida, and Argentina and probably exists in most other areas. Whether it could do much damage to healthy citrus trees is a moot point. In recent years, however, more and more workers in California have been inclined to blame it for poor tree condition and their inability to replant citrus with citrus satisfactorily. The idea that nematodes are of importance has been stimulated by the finding in Florida that the cause of spreading decline is the burrowing nematode, Radopholus similis (Cobb) Thorne. This nematode, hitherto unknown as a citrus pest, destroys the feeder roots particularly below a depth of about 2 feet and has been found to a depth of 14 feet. In the course of this work a number of other nematodes, hitherto unreported on citrus, have been found and at least some of these appear to damage citrus roots. The indications are that nematodes are going to be one of the real citrus problems of the future. 

Thompson, C. R., and O. C. Taylor. Effects of air pollutants on growth, leaf drop, fruit drop, and yield of citrus trees. Environ. Sci. Technol. 3 934-940. 1%9. 

Petitgrain oils are obtained by steam distillation of the leaves of citrus trees. The oils derived from the bitter orange tree are the most important. Other petitgrain oils (mandarinier, citronnier, and bergamottier) are less important. Petitgrain oil mandarinier is a source of natural methyl A -methylanthranilate, which is present at a concentration of nearly 50%. Petitgrain oils are essential constituents of eau de cologne. 

Until further information is obtained on the response of citrus trees to differences in the composition of petroleum oil, estimation of the practical value of the differences indicated between the two series of petroleum fractions on the basis of viscosity, in the control of citrus red mite, is limited. However, the conventional spray oils used in southern Califomia for the control of citrus red mite are applied at dosages six to seven times the LDm values indicated in Figiue 4 for oils having a molecular weight of 340 or above. Proper selection of oils with respect to molecular weight might make it possible to achieve good field control of citrus red mite with applications of much smaller amounts of oil. 

II, 2-dihydro-3.6-pyridazinedione) is used to inhibit the growth of certain food commodities when in storage, including onion and potato. Maleic-hydra/ide is also used to promote dormancy in citrus trees as well as increasing protection from Irosi. 

Citrus trees are capable of translocating limonoids from leaves to fruit tissues (12). When 20,000 cpm of XIV, randomly labeled, was fed to a leaf adjacent to a 5-g-size lemon, about 13.3% of the total activity was translocated to the fruit during 20 hrs. These findings of Hasegawa et al. (12,13) show that limonoids in citrus fruit tissues are synthesized in leaves and translocated to the fruit. 

The common citrus fruits belong to three genera, Citrus, Poncirus (trifoliate orange), and Fortunella (in the Rutacea family) (Castle, 1987). Hereafter, citrus will refer to any or all of these three genera. The citrus tree is a native of Southeast Asia (Woodhead, 1981). 

California trees, citrus tree trunk and canopy growth, leaf nitrogen level, fruit yield, and fruit quality were decreased by competition from annual weeds and bermudagrass (Jordan, 1981). Suzuki (1981) reported that in Japan, weeds in summer absorb and transpire large amounts of water from the soil and compete with citrus trees. Moisture and nitrogen levels in the soil decreased particularly where large crabgrass and tufted knotweed were present (Ito and Ukei, 1981). 

Citrus trees are a long-term investment, and growers cannot afford crop damage or yield loss from weed competition, cultural operations, or misapplication of chemicals. The most critical time to control weeds in trees is from planting to early establishment, which spans from 3 to 6 years depending upon soil fertility. 

Bredell, C.S. (1973). Response of citrus trees to plastic mulching. Proceedings of International Society of Citriculture. 387-394. 

Jordan, L.S., B.E. Day, and R.C. Russell (1969). Herbicides in citrus trees and soils. Proc. 1st Inti. Citrus Symp., 1 463-466. Riverside, CA University of California. 

Chlordecone was used as an insecticide on tobacco, ornamental shrubs, bananas, and citrus trees, and in ant and roach traps. Mirex was sold as a flame... 

Gas used as a fumigant for citrus trees, and in ships and buildings against rodents and vermin salts used for case-hardening steel Possesses a peculiar peach blossom odor nausea and vomiting feeble pulse shallow breathing dyspnea cyanosis convulsions and collapse... 

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. 

Using individual citrus trees which were exposed to clean or smog-polluted air, Thompson and Taylor (36) and Thompson et al. (37) were able to show a reduction in crop yield from trees growing in unfiltered air. They showed that the combined pollutants in smog caused reduced water use, reduced photosynthesis, increased leaf and fruit drop, and severe reduction in yield. All of these changes occurred without the appearance of any visible injury to the leaves or fruit. 

Drop, Fruit Drop and Yield of Citrus Trees, Environ. Sci. Technol. (1969) 3, 934. 

Increase the distance between the rows of citrus trees from 6 to 9 metres, cutting down several rows of citrus trees. Lower-density plantings are better adapted to the organic production system they increase ventilation and light interception and thus decrease disease pressure. Lower tree density gives space for crops in the alleyway between rows. 

Between the rows (in the alleyway) it may be possible to intercrop permanently with pasture (sheep), beans or other crops. However, this may be difficult in the case of older plantations where the trees are adapted to a certain type of management in such cases, a step-by-step procedure is recommended (introduction of new crops and elements at yearly intervals), to allow the root systems of the citrus trees to adapt to new competition in the soil. For larger, mechanized organic farms it may be difficult to continue intercropping as soon as the newly planted citrus trees are in production. In such cases, cover crops may be more appropriate in order to avoid disturbances in citrus management. 

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