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M. Ahmedullah

Fruit of table grape cvs. Black Monukka, Flame Seedless, Thompson Seedless and Himrod were fumigated with 2, 4 and 6 Deccodione tablets for 30 minutes in a fumigation chamber. Fruit was brought to the cold rooms and stored at 32 F and high relative humidity for upto 10 weeks. Decay control index, freshness of stems and bleaching around the capstem were recorded at 2, 4, 6, 8 and 10 weeks of storage. Size of the smoke particles was determined using an electrical aerosol analyzer.

Fruit was kept in good condition by fumigation with 6 smoke tablets upto 10 weeks. Lower doses failed to control the decay. No bleaching around the capstems commonly associated with sulfur dioxide fumigation was noticed. Majority of the smoke particles were between 0.18 and 0.32 micrometers. Fumigation with Deccodione tablets could be a viable alternative to sulfur dioxide fumigation.

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M. Ahmedullah

The extent of translocation of 14C-labeled photosynthates from the senescent leaf to the parent vine before leaf abscission and the short-term effects of premature leaf removal on the carbohydrate balance of the vine were studied by using autoradiography and trapping 14CO2 respired from the treated leaf. The treated leaf abscissed 1.5 days after administering the label. The plant was harvested after natural leaf abscission. The radioactivity recovered from the plant, excluding the treated leaf, was 20% of the input. Radioactivity was detected in the roots, trunk, shoot, and leaves. Most of the radioactivity remained in the trunk and the young and old roots. The implications of premature leaf removal by mechanical harvesting on the carbohydrate balance of the vine are discussed.

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M. Ahmedullah and P. Bristow

Concord blueberries treated with biocontrol fungi (Trichoderma and Gliocaladium) both at 1 and 2x rates and with fungicides benlate + captan + B 1956 and Tween for controlling botrytis flower blight were stored at 32F. Trichoderma (2x)-treated fruit was 71% without infection; Gliocaladium (2x)-treated fruit 69%, compared to 57% from untreated control. Momentum Transfer Generator (MTG) readings indicating fruit firmness ranged from 474 to 494 for the above treatments, indicating that fruit firmness was not affected by the treatments. Concord blueberries from bushes infected with blueberry scorch carla virus showed no difference in fruit firmness compared to healthy berries either before or after 7 weeks of storage at 32F.

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M. Ahmed Ahmedullah

On potted Carignane grapevines, the following three leaf removal treatments were used: 1) six basal leaves allowed; 2) all leaves left on the vine; and 3) all leaves left on the vine except shoot tip, darkened by covering the leaves with aluminum-coated paper bags. Translocation and use of photosynthates was studied using C14 in the season of application and in the following year. In the season of C14 application, the roots and trunk were the major sinks. Reserve photosynthates were used to support current-season growth following budbreak in all three treatments. Treatments 1 and 2 showed similar trends in use of reserves; in treatment 3, however, reserves continued to be used until harvest at full maturity. Defoliated vines used more stored reserves than nondefoliated vines. Defoliated vines used more reserve carbohydrates, leaving little C14 reserves in old roots compared to nondefoliated vines.

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M. Ahmed Ahmedullah

Fruit of Vitis vinifera cvs. Flame Seedless, Thompson Seedless and Black Monukka were fumigated with 4, 6 and 8 Deccodione Smoke Tables (DST) for 30 minutes. Fruit was stored at 32 F and high relative humidity. Decay control index, freshness of stems and bleaching around the capstem were recorded at 4, 8, 12 and 16 weeks of storage. Size of the aerosol particles was determined using an electrical aerosol analyzer. Fruit was analysed for Deccodione residues.

Lower rates of the fungicide gave unsatisfactory decay control. Eight DSTs successfully controlled decay upto a period of 14 weeks. There was no bleaching of pigments commonly associated with sulfur dioxide fumigation. Majority of the aerosol particles were between 0.18 and 0.32 micrometers. Deccodione residues on the fruit were within the acceptable limits established for Deccodione. There was no perceptible difference in taste between treated and control fruit. This method of decay control could provide a viable alternative to sulfur dioxide fumigation.

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S. Gurusiddaiah and M. Ahmedullah

For the control of Reeds Canary grass (Phalaris arundinaceae) and yellow nutsedge (Cyperus esculentus) in blueberry fields, no satisfactory control measures are available. We tried microbially derived aerobic fermentation extracts of Pseudomonas syringae strain 3366 (P. S. 3366) as pre- and -post-emergence applications for the control of Reeds Canary grass and yellow nutsedge. In greenhouse studies using “conetainers,” 2 mg of extract per g of soil applied as preemergence completely inhibited seed germination and aerial growth of Canary grass, but had no effect on nutsedge. In addition, the same level of concentration of P. S. 3366 (2 mg of extract/g of soil) under field conditions also showed 99% inhibition of germination and growth of Canary grass, but had no effect on germination of nutsedge. However, 4-fold increase in concentration of P. S. 3366 extract completely inhibited the sprouting of yellow nutsedge in greenhouse studies. These studies indicate microbially derived extract of P.S. 3366 can be used and has potential for the control of these weeds. Post-emergence foliar sprays of P. S. 3366 extract in blueberry fields failed to inhibit the aerial growth of Reeds canary grass and yellow nutsedge.

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M. Ahmedullah and C. R. Rom

Roots of one year old grape cvs. Concord, White Riesling, Grenache and Semillon were frozen to 0, -5, -10, -15 and -20°C in a programmable freezer. The tops were protected from cold by insulating them. For survival test, 4 plants of each cv. were planted in the greenhouse and their growth observed. Differential thermal analysis (DTA), using a computer attached to a programmable freezer was performed on roots. To aid in the interpretation of DTA, triphenyltetrazolium chloride (TTC) was performed. Hardiness determinations were based on DTA, TTC and the survival tests. DTA patterns representing exothermic response showed an exotherm associated with extracellular free water in tissue which appeared at about the same temperature range for all cvs. This is not associated with hardiness. Additional minor exotherms related to hardiness appeared at lower temperatures than the extracellular water exotherm. Their location differed from one cv. to another. Based on these tests, Concord roots appear to be hardier than other cvs. with important but minor differences in the hardiness of other cvs.

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M. Ahmedullah and C. R. Rom

Roots of one year old grape cvs. Concord, White Riesling, Grenache and Semillon were frozen to 0, -5, -10, -15 and -20°C in a programmable freezer. The tops were protected from cold by insulating them. For survival test, 4 plants of each cv. were planted in the greenhouse and their growth observed. Differential thermal analysis (DTA), using a computer attached to a programmable freezer was performed on roots. To aid in the interpretation of DTA, triphenyltetrazolium chloride (TTC) was performed. Hardiness determinations were based on DTA, TTC and the survival tests. DTA patterns representing exothermic response showed an exotherm associated with extracellular free water in tissue which appeared at about the same temperature range for all cvs. This is not associated with hardiness. Additional minor exotherms related to hardiness appeared at lower temperatures than the extracellular water exotherm. Their location differed from one cv. to another. Based on these tests, Concord roots appear to be hardier than other cvs. with important but minor differences in the hardiness of other cvs.

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M. Ahmedullah and Alex Ogg Jr.

Field grown high and low vigor Vitis labruscana cv, Concord grapevines were sprayed with 2,4-D amine in concentrations of 0, 2.5, 10 and 25 ppmw at 1st leaf; 1st and 3rd leaf; 1st, 3rd and 5th leaf and 1st, 3rd, 5th and 7th leaf stages of vine growth for two consecutive years. Cane and bud samples were collected for determining node diameter, internode length, carbohydrates in the canes, and T50 of buds. Data on yield and vegetable growth were also collected.

There were significant differences among treatments in the node diameter and cold hardiness of buds (T50) both in high and low vigor vines. Repeated applications of 2,4-D reduced the cane diameter significantly but the carbohydrates in the canes were not affected. When 2,4-D symptoms were severe in July, yields were reduced by as much as 85%, but there was slight or no reduction in yield when symptoms were not severe.

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M. Ahmedullah, M. E Patterson, and G. Apel

Table grapes cvs. Flame Seedless, Black Monukka and Canadice and blueberries cvs. Bluecrop and Northland were exposed to chlorine dioxide (C102) gas under laboratory conditions. Chlorine dioxide was generated chemically. Grapes were fumigated in a plexiglass chamber with C102 for 30 minutes, packed in TKV lugs with Botrytis inoculum planted among the clusters and stored at 0° C for 8 weeks. Blueberries were consumer packed with 5, 10, and 15 gr. Absorb (C102 generator) in Tyvex sachets, enclosed in pillow-pak bags and stored at 0° C for 75 days and at 20 or 30° C for 16 days.

At periodical intervals, moisture loss, decay and quality parameters were evaluated. Chlorine dioxide caused bleaching and skin injury around the capstem on blueberries but not on grapes. Decay was reduced with C102 treatment but moisture loss increased in blueberries. We could store grapes for two weeks without fungal growth. Storage for longer periods necessitated treatment with higher concentrations of C102 which were not generated under our laboratory conditions.