Apples harvesting

Summer strawberries, fall apples— harvesting your own fruit makes you more aware of seasonal change. 

Effect of ethephon in combination with daminozide or 2,4,5-TP on the quality of Worcester Pearmain apples harvested on Aug. 25th... 

Fruits are seasonal in temperate climates, and a good harvest may be followed by a shortage if there is no method of preservation. The hard fruits, apples and pears, have traditionally been stored in cool places and may then last for several months, depending on the variety Refrigeration has extended the storage life, and made this more reliable. 

Sampling Golden delicious apples were sampled in intervals of three weeks over a hole season. Sampling started at the so-called June-drop , which corresponds to the end of the cell division phase (= week 0). After harvest (week 14), the mature apples were stored over a period of 20 weeks at 4°C and 95% relative humidity. 

Stable in acidic, neutral and basic aqueous solutions Pale yellowish solid, faint characteristic odor Flash point 119°C (Pensky-Martens closed tester) Pyriproxyfen is an insect growth regulator which acts both as an ovacide and as an inhibitor of development (juvenile hormone mimic) against white flies, scale, and psylla. The specificity of pyriproxyfen, and its low mammalian toxicity, allow for some variation in application timing. For example, the lack of toxicity to bees allows pyriproxyfen to be applied during bloom on apple trees, and its low mammalian toxicity allows for a very short pre-harvest interval on citrus The residue definition is for pyriproxyfen alone... 

The determination of DDT residue on apples grown in the Hood River fruit district and on pears at Medford is carried on in branch laboratories established in those areas. The majority of samples selected for analyses are suspected of carrying higher amounts of residue than the average because of the spray program used or because the last application of insecticide was made within a few weeks of harvest. As indicated by Table I, about 80% of all the samples analyzed carried 3.0 p.p.m. or less of DDT during the past harvest season. Only about 20% of the samples showed residues above 3.0 p.p.m. six samples showed residue deposits slightly above 7.0 p.p.m. 

In the eastern United States apples of the Delicious variety treated 10 days prior to harvest with pure gamma isomer showed no trace of off-flavor at harvest time. Dusts and sprays applied to carrot seedlings produced no traces of off-flavor in the mature vegetables. Several tasters could not differentiate between peaches sprayed within a few days of harvest and check fruit. Celery in Florida sprayed twice, once within 6 weeks of harvest and once within 30 days of harvest, was canned and put through a severe series of tests. 

A sample of hops which had been treated with tetraethyl pyrophosphate showed a negative chemical analysis. The plant material was also extracted and the extract added to the drinking water of test animals and sensitive insects. The animals and insects that drank this treated water for several days showed no reaction. With the sensitive insects it would have been possible to detect even a few parts per million. In addition, there have been extensive commercial field applications of the chemical in dust and spray form to crops such as apples, pears, grapes, celery, broccoli, Brussels sprouts, and others up to within a few days of harvest there has been no detectable poison residue on any of the crops. The lack of poison residue with use of tetraethyl pyrophosphate is due to the fact that it hydrolyzes within a few hours of application, breaking down into transient nonresidual and nonpoisonous chemicals. Thus it is possible to use tetraethyl pyrophosphate well up to harvest time of food products without danger of residual poison on crops. The fact that the chemical is used in extremely small amounts is a definite advantage in respect to freedom from poison residue. 

Surface residues of DDT and parathion at various times during the season and at harvest were determined for apples, pears, peaches, oranges, and lemons. Low level surface residues of parathion on apples were not carried over into cider. Harvest residues on fresh fruit are distinguished from residues present in food at the time of consumption which are included under the designation ultimate residues. 

Table I. Surface Residues of DDT on Rome Beauty Apples at Harvest...

Surface residues of DDT on apples resulting from experimental applications applied in schedules comparable to commercial usage ranged from less than 0.5 to 2.0 p.p.m. at harvest. Schedules of application involving higher spray concentrations and greater frequency of application than are at present required in commercial practice resulted in most cases in residues of less than 7 p.p.m. Typical harvest residues are presented in Table I. 

Intervals between application and sampling of apples retaining weathered surface residues of parathion ranged between 21 and 70 days. At harvest, these residues were 0.05 p.p.m. or less, following each of 13 varied schedules of application (Table III). (These values are derived from samples containing an optimum amount of parathion for analytical precision.) Low level surface residues on apples were not carried over as ultimate residues in cider (Table III). This fact supports the contention that there is close association of the parathion deposits with the waxlike coating of the fruit. 

The tests reported were conducted in 1948 on apples growing in the Yakima Valley in the Pacific Northwest and in the Mississippi Valley, to determine the magnitude of parathion and DDT spray residues at harvest. The climates and spray schedules differ markedly in the two areas consequently, spray residues also differ, and are larger in the Mississippi Valley than in the Yakima Valley. 

Table I shows the parathion residues on Delicious and Winesap apples in the Yakima Valley immediately after the last spray application and at intervals until harvest. Parathion was used at two concentrations, both as close as possible to the minimum necessary to give the desired control. Consequently, the residues found were comparatively low and dropped to 0.1 p.p.m. or less in approximately 2 weeks.

On Delicious apples the initial residues were 0.9 and 0.4 p.p.m. in plots 7 and 10, respectively, both of which were sprayed with 1.25 ounces of parathion. The difference between the two plots was consistent throughout the individual trees sampled. The spray mixture used on plot 7 also contained DDT, while that used on plot 10 contained only parathion. These plots showed the same relative magnitude of residues 18 days after spraying, and at harvest, 74 days after the spraying. Plot 11, sprayed with 0.6 ounce of parathion. showed an initial residue of 0.3 p.p.m. 

Initial residues on the Winesap apples were somewhat higher than those on Delicious. Six days later approximately one third of the residue had been lost, and 12 days after the spraying the deposits were down to 0.10 and 0.03 p.p.m. for the respective strengths. At harvest little more than a trace of parathion was found on the fruit. 

Plots 12 and 13 afford a comparison of the harvest residues from first- and second-brood sprays. On plot 13, which was sprayed on May 11 and 20 and June 3 and 16, the parathion residue was only 0.1 p.p.m. on July 30 and none in subsequent samplings. On plot 12, which received two sprays on July 7 and 28, the residue on Jonathan apples was 1.23 p.p.m. on July 30 and 0.09 on September 14. 

Table IV gives the data from seven plots of Winesap and Rome Beauty apples in the Mississippi Valley. The spray schedules are similar to those used for the plots included in Table III, except that an additional parathion spray was applied on plots 9, 11, 14, and 4 on August 19, and the final harvest sample was taken on October 5. Only on the plot that was sprayed seven times with the 8-ounce strength of parathion (plot 14) did the spray residue at harvest approximate 0.1 p.p.m.

Table V shows the DDT spray residues at harvest on Delicious and Winesap apples in the Yakima Valley. Most of the Delicious plots received two sprays containing DDT, the last one 97 days before harvest. The Winesap plots received four sprays containing DDT, the last spray 74 days before harvest. The harvest residues in the Winesap plots were significantly higher than those in the Delicious plots, but were less than one half the proposed tolerance of 7 p.p.m. of DDT.

Table VII shows the residues of DDT at harvest in the Mississippi Valley on Jonathan and Starking Delicious apples on which a six-spray schedule was used. All plots except plot 8 were sprayed six times with DDT at 8 ounces to 1 pound per 100 gallons. Plot 8 received only four sprays, three containing 1.5 pounds and one containing 1 pound...

Table VIII shows the residues of DDT at harvest on Rome Beauty and Winesap apples in the Mississippi Valley. The plot treatments are the same as for Jonathan and Starking Delicious apples (Table VII) except that a seven-spray schedule was used. The residues at harvest shown in Table VIII are greater than those in Table VII. A comparison shows that when six cover sprays of DDT are applied without adhesives the harvest residues are approximately 7 p.p.m. or slightly more. If, however, seven cover sprays are applied, the residues may exceed 9 p.p.m. of DDT, unless the concentration is reduced to less than 1 pound of DDT in 100 gallons.

Cover sprays, at concentrations ranging from 0.25 to 4 pounds of the 25% wet-table parathion powder per 100 gallons of water, were applied to Delicious apples. These sprays were applied on June 7, July 2, and August 3. The residue samples were selected at harvest time and held in cold storage (32° F.) for a period of time and then analyzed. The elapsed period of time between spraying and analysis was 90 days. The results are presented in Table IV. 

In practically all cases the residual DDT was reduced to less than 1 p.p.m. fresh weight. However, some of the apples used in the 1944 tests carried as high as 9.5 p.p.m. of DDT as surface residue, whereas subsequent deposits prior to washing averaged about 2 p.p.m. From these and supplemental tests it would seem that such small harvest residues of DDT... 

Further wash tests with apples and pears have not been extensive because the magnitudes of typical DDT harvest residues suggest that no appreciable difficulty will be encountered in bringing fruits sprayed with the lower dosages under the provisional tolerance for DDT residues on these fruits. 

We measured many properties of the soil, the growing trees and the apples after harvest and after storage. The results were studied in relation to the management factors and mutual correlations were computed. This procedure enabled us to contribute to the validation of the IQC (step 3, Table 5.3), the validation of new parameters (steps 5 and 6) and the evaluation of orchard management. Details of the methods and results of the apple series are described elsewhere (Bloksma et al., 2001, 2004). Here, we mention only some of the results that are relevant to the IQC. 

Further insight on the frequency of multiple residues is evident in Table 14.4, which shows the number of residues found per sample for selected foods tested in 2004 by the PDP. Conventional apples were found to contain, on average, 3.6 residues, while the one positive organic sample had a very minute level of the post-harvest fungicide thiabendazole. The level of residue found in the one positive organic apple sample was 0.0002 parts per million, while the mean thiabendazole residue found in 641 positive conventional samples was 0.43 ppm, over 2100 times higher than the level found in the organic sample. 

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