CORRECTION OF MOLYBDENUM DEFICIENCY

Transcription

1 4 FLORIDA STATE HORTICULTURAL SOCIETY, 95 ing the digging and packing operations if bulk handling equipment is used. This problem will be particularly difficult in a house that packs for several growers unless a satisfactory method of temporary storage can be developed. Pota toes dug mechanically will contain more dirt and trash than potatoes dug with present methods. This mean some adjustment will be necessary in packing house equipment and operation in order to remove the dirt and trash before the potatoes enter the washing ma chines. Increased mechanization will increase cap ital requirements for those in the potato in dustry. It will also increase the danger of loss at times of very adverse harvesting con ditions. However, the trend to mechanical equipment will continue. The speed at which it is adopted will depend on the success in solving the problems involved. Mr. A. H. Glaves, Agricultural Engineer of the Bureau of Plant Industry, Soils, and Agri cultural Engineering of the U.S.D.A., who is in charge of the agricultural engineering phase of the research work on mechanical harvesting at the Red River Valley Potato Research Cen ter, lists the following factors as affecting the successful operation of an individual ma chine: V. The Soil and Topography.. The cropping system, or immediately preceding crop sequence. 3. Good seed (Because it will contribute to an even stand, uniform tuber size and maximum yield.) 4. Proper spacing of seed and an even stand. From a talk presented at the 95 Annual Con vention of the Ohio Vegetable and potato Grow ers Association, Cleveland, Ohio, February 8, Good tillage practices and good weed control. Potato variety and its characteristics. Effective vine treatment without objec tionable soil packing. The weather during the harvest period. (If you have high capacity in your har vester and complementary handling equip ment, you can more nearly choose your weather.) The operator and good crew manage ment. The adaptability and design of the ma chine. Availability of repairs and dealer service when needed. Troubles and deficiencies most frequently encountered are listed by Mr. Glaves in their general order of importance are as follows: V. Vine and trash elimination Tuber damage. Incomplete recovery or spill-out. (Often due to poor scouring of the blade.) Clod and stone separation. Lack of slip clutches or other protective devices. Hazards to workers. (Devining rolls or any other unguarded moving parts.) Machine weaknesses and misalignment under field stresses. (These are being gradually corrected as they show up.) Soil elimination in sticky conditions. (The indirect method is especially advantageous under these conditions.) Crew coordination and management re quires experience to reach maximum ef ficiency. CORRECTION OF MOLYBDENUM DEFICIENCY IN CAULIFLOWER A. H. Eddins, E. N. McCubbin, Nathan Gammon and G. M. Volk Florida Agricultural Experiment Station Gainesville Florida Agricultural Experiment Station Journal Series, No. 95. Cauliflower, broccoli, brussels sprouts, cab bage and Swede turnips are reported to be sus ceptible to molybdenum deficiency (9). The deficiency is generally known as whiptail in cauliflower and broccoli. It has occurred in cauliflower grown in England (7), Australia (9), New Zealand (6), and the United States (). Heavy losses from whiptail were report-

2 EDDINS, McCUBBIN, GAMMON, VOLK: MOLYBDENUM DEFICIENCY 5 ed by Clayton () in 94 in cauliflower crops grown on acid soils in New York. Whiptail also occurs in West Virginia and New Jersey () and it has been troublesome in the Hast ings section, Florida, particularly in soils with reactions of ph 5. and lower (4). If molybdenum is deficient in plant bed soils, some seedlings develop abortive buds or form stubby growing points. Whip tail-affect ed plants may be stunted and bear narrow, ruffled and rolled leaves with irregular mar gins, Fig.. They may fail to curd or may produce loose, ricey curds with deformed leaves in the curd, Fig.. Adventitious buds may form on the lower part of the stem of a severely-affected plant after it is transplanted to soil containing available molybdenum and the shoots or suckers may produce small curds. In 945 Davies () demonstrated that whiptail which developed in cauliflower in New Zealand was due to a deficiency of molybden um. Later Hewitt and Jones (5) produced whiptail symptoms in cauliflower plants grown in sand cultures from which they withheld molybdenum. Plant (7) reported molybden- Fig.. Cauliflower curd from a whiptail-affected plant. um deficiency in England in cauliflower and broccoli grown in soils with reactions of ph 4.5 to 6.5. He controlled the trouble by liming acid soils, by applying small amounts of sodi um and ammonium molybdate to the soil and by spraying seedlings with solutions of these chemicals. Stewart and Leonard (8) reported molybdenum deficiency of citrus in Florida and found that it could be corrected by spray ing the trees with sodium or ammonium molyb date. English and Australian workers (7,9) concluded that molybdenum may be present in acid soils but unassimilable by crops, and that it may be actually deficient in some weak ly-acid and non-acid soils. They found that soils really deficient in molybdenum did not respond to liming but were benefited by dress ings of molybdenum. Treatments Tested for Control of Whip tail at Hastings, Florida Fig.. A cauliflower plant affected with whiptail. In a small plant bed at Hastings in the 95-5 season, 88 percent of Snowball A cauli flower plants developed whiptail when grown in soil testing ph The deficiency was almost eliminated in plants grown in sections of the plant bed where the soil had been ad justed to ph 5. with hydrated lime, or by spraying the seedlings and soil with an ammonium molybdate solution (.35 lbs. (NH4)Mo7O4-4H,,O- gals, water per acre). The tests were made with small numbers of plants but results obtained are similar to those reported by Plant (7), who worked with the same materials in England. Varieties of cauliflower grown in soil of dif ferent ph reactions in 95 and 95 differed in their susceptibility to whiptail, Table. The symptoms appeared more often in plants grown in the most acid soil. and varieties of the type, which include Holland

3 6 FLORIDA STATE HORTICULTURAL SOCIETY, 95 Erfurt, Snowdrift, Improved Holland Erfurt, Snowball 6 (Imported and Domestic), Snow ball E and Y, were more resistant to whiptail than those of Snowball A type, which include Snowball A, Super Snowball, New Strain and Earliest Dwarf Erfurt. More extensive tests on control of whiptail were conducted in a plant bed and in the field in the season to better determine the responses to corrective measures. The whiptail-susceptible variety, Snowball A, was used in these tests. PLANT BED The seed was sown in soil testing ph 4.5 to 5.3. The plant bed was fer tilized a few days before seeding with, pounds of a fertilizer per acre. No mi nor elements were added to the fertilizer. The plants and surface of the soil in the treated plots were sprayed with a sodium molybdate solution (.5 lbs. 65 gals, water/acre) days after the seed was planted. The plants were thinned to a stand when seven weeks old and then fertilized with another, pounds of fertilizer per acre. Thereafter, they were side-dressed three times at 3-week intervals with 5 pounds per acre of ammonium ni trate or Arcadian nitrate of soda at each ap plication. Ninety-five to percent of the non-treated plants were affected with whiptail in plots where the soil tested ph 4.5 to 5. and 7 percent of those in soil testing ph 5.3 were affected with the trouble. The difference in number of plants affected with whiptail in sprayed and non-sprayed plots is highly sig nificant, Table, and the test demonstrates that whiptail can be controlled by spraying young seedlings and soil with a weak solution of sodium molybdate. Table. of Snowball A Cauliflower Plants Affected with Whiptail in Thinned Plots When the Seedlings Were Sprayed with Sodium Molybdate (.5 lbs. 65 gal. wa ter/acre).* Treatment** Sprayed Not Sprayed Odds Average 4 3 Plants per Plot*** Affected with Whiptail 8 4,999: Soil reaction ph Replicated 6 times in rows 5 hills long and 4 inches apart. Seed planted /5/5; plants sprayed /5/5 and thinned to a stand //5. TRANSPLANTED FIELD - Three mate rials were tested as soil treatments. Hydrated lime was broadcasted and disked into the soil and solutions of sodium molybdate and borax alone and in combination with each other were poured in a shallow furrow in tops of the rows and the furrows were filled with soil about a month before the plants were set. Plants used in this experiment were grown in non-treated acid soil. The plots were six rows wide, but only one row in each plot was used in this experiment. The soil was fertilized with,85 pounds of a fertilizer per acre without minor elements before the plants were set; later they were side-dressed three times at in- Table. P ercentages of ph Reactions. Whiptail Plants in Different Varieties of Cauliflower Grown in Soil of Different Date Soil /4/5 //5 Reaction Unknown* ph Variety Snowball A Holland Erfurt Super Snowball Snowdrift Improved Holland Erfurt Snowball 6 (Imported) Snowball 6 (Domestic) Snowball E Super Snowball Snowball Y Snowdrift New Strain Earliest Dwarf Erfurt Total Plants Affected o o 6 5 with Whiptail Percent //5 4/8/ Snowball A * Reactions in nearby rows ranged from ph 5. to 5.4 October 7, 95.

4 EDDINS, McCUBBIN, GAMMON, VOLK: MOLYBDENUM DEFICIENCY 7 tervals of about three weeks with enough ammonium nitrate or Arcadian nitrate of soda to supply 4 pounds of nitrogen per acre at each application. Five of the 5 plants re quired to set each plot showed symptoms of whiptail when they were transplanted. Soil in the plots varied in reaction from ph 4.6 to 5.8, depending upon the season and whether or not it had been treated with hydrated lime. When sodium molybdate was applied to the soil alone or in combination with hydrated lime and borax no whiptail developed, and the treat ment corrected the deficiency in five plants in each plot that were affected when trans planted, Table 3. Only four plants in each plot treated with borax and sodium molybdate were affected, compared to 3 affected plants grown in the non-treated plots. The differ ence in the number of whiptail-affected plants in the non-treated and limed plots also was significant, but liming alone to an average ph of 5.5 was not sufficient to give complete con trol of whiptail the first year. Conclusions Results obtained from treating soil and cau liflower plants with sodium molybdate and ammonium molybdate at Hastings, Florida, are similar in many respects to those obtained from treatments with the same materials in England (7), Australia (9) and New Zealand (6), and demonstrate that whiptail is caused by a de ficiency of molybdenum. Repeated additions of molybdenum to an acid soil will result in a steady increase in this element in the soil, as it is less likely to leach from an acid soil than one of neutral ph. It may be possible that under acid conditions, ad dition of molybdenum would have to be made every year. If, then, at some future time the field was limed and put into pasture the cat tle grower might be in very serious trouble, since under certain conditions herbage contain ing even less than ppm. molybdenum may be toxic to cattle (3). The responses that have been obtained by use of lime indicate that soils in the Hastings area contain some molybdenum that can be made available for cauliflower growth by in creasing the ph. Since availability of molyb denum is known to increase with increasing soil ph, and since these observations cover only ph values up to about 5.5, it is possible that sufficient molybdenum to prevent whip tail may become available if the soils are raised to higher ph values. The real value of liming is still unknown because the effect may be slow and not fully apparent the first year. It is not known whether sufficient molybdenum can be made available for normal cauliflower growth by increasing the ph of these soils, but it is hoped that this will be determined by more elaborate tests now under way. Pending the completion of those tests on the molybden um-supplying power of these soils, it is recom mended that whiptail-resistant varieties of cau liflower such as, be grown and that the soil in seedbeds and fields be limed to at least 5.5. LITERATURE CITED. Clayton, E. E. Investigations of cauliflower diseases on Long Island. N. Y. Agr. Exp. Sta. Bui Davies, E. B. A case of molybdenum deficiency in cauliflower. Nature 56: Davis, G. K. Copper Metabolism, A Symposium on Animal, Plant and Soil Relationships. Mc- Table 3. of Snowball A Cauliflower Plants Affected with Whiptail when Grown in Soil Treated with Three Materials in 95. Soil Treatment* Sodium molybdate (4 lbs. gals, water/acre) Hydrated lime (,5 Ibs./acre) Borax ( lbs. gals, water/acre) Borax-sodium molybdate ( lbs. 4 lbs. gals, water/acre) Borax-sodium molybdate-hydrated lime ( lbs. 4 lbs. gals, water,5 Ibs./acre) Check (No treatment) Least Significant Difference 5% Soil Reaction ph // /8/ Average 4 Plants per Plot** Average Affected with Whiptail Each replicated 3 times in randomized plots with plants foot apart in rows 5 feet long and 4 inches apart. Lime applied /7/5; other treatments made //5. Transplanted //5.

5 8 FLORIDA STATE HORTICULTURAL SOCIETY, 95 Elroy and Glass, Editors. Johns Hopkins Press Eddins, A. H. Diseases, deficiencies and injur ies of cabbage and other crucifers in Florida. Fla. Agr. Exp. Sta. Bui Hewitt, E. J., and E. W. Jones. The produc tion of molybdenum deficiency in plants in sand culture with special reference to tomato and Brassica crops. Jour. Pomol. and Hort. Sci. 3: Mitchell, K. J. Preliminary note on the use of ammonium molybdate to control whiptail in. cauliflower and broccoli crops. N. Z. Jour. Sci. and Tech. 7A: Plant, William. The control of whiptail in broc coli and cauliflower. Agriculture 57: Stewart, Ivan, and C. D. Leonard. Molybdenum deficiency in citrus. Proc. Fla. State Hort. Soc. 64: Waring, E. J. Molybdenum deficiency in cruci ferous crops. Agr. Gaz. 6: Weiss, Freeman. Index of plant diseases in the United States. U.S.D.A. Plant Dis. Survey. Part II: SOME FACTORS AFFECTING PRODUCTION OF BROCCOLI AT HASTINGS E. N. McCubbin Florida Agricultural Experiment Stations Potato Investigations Laboratory Hastings Broccoli has grown in popularity within re cent years as a fresh and frozen vegetable. Several hundred acres of the crop are grown each year in Florida to supply the demand for this commodity. Broccoli was planted on a commercial scale at Hastings, Florida, for the first time in 95, but growers met with little success as freezes destroyed most of the plant ings. Varieties of broccoli were tested at the Po tato Investigations Laboratory, Hastings, from 95 to 95. Results of those tests and ef fects of temperatures on growth of the crop are discussed in this paper. Variety Tests Twenty-four varieties and strains of broccoli were tested. The plants were grown in plant beds and transplanted to the field each year in November or December. They were set two feet apart in 5-foot, single-row plots of Bladen fine sandy loam soil. Rows were 4 inches apart and each variety was replicated 4 times. A fertilizer, containing. per cent B-Oa from borax, was applied in a band in both sides of the row at the rate of,8 to, pounds per acre a few days before the plants were set. The rows were rebedded to a height of 8 to inches and boarded-off, leaving the fertilizer to 3 inches below the soil surface. When the soil was dry, it was irrigated lightly a few hours be- Florida Agricultural Experiment Station Journal Se ries, No. 98 fore the plants were set and immediately thereafter to insure a better stand of plants. The plants were cultivated when necessary to control weeds and to aerate the soil fol lowing heavy rains. They were irrigated when needed and side-dressed or 3 times during the growing season with 5 to pounds of nitrate of soda or nitrate of potash per acre per application. Insects and diseases were controlled by regular applications of the proper insecticides and fungicides. The broc coli was harvested at - to 4-day intervals for 4 to 79 days in the different years. Central flower buds in top of the plants and lateral buds or side-shoots, which develop in leaf axils along the main stem after the central flower buds are removed, are the parts har vested. The flower buds were cut to a length of 5/ inches before they opened and before stem tissues became tough and woody. Yields of the different varieties and strains of broccoli varied from 4,3 to, pounds per acre, Table. Side-shoots comprised to 8 percent of the total yields. Of the 5 varieties and strains grown either two or three years, three strains of Early Green Sprout ing, which are suitable for fresh-market and freezing, matured early and produced the highest average yields. DeCicco matured early and ranked second in yield, but the bud sepals may be too large to make a prime freezepack. Other varieties which matured early and produced good yields were Freezers Green Sprouting, Texas 7 and Early Green 953. However, flower buds of Texas 7 may be too yellow for freezing. Early One, Waltham and Early DeCicco also matured early, but they produced rather low yields. Early Propagano, Early 949 and Waltham