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Vegetable Crops Edition May 5, 2010

PLANT & PEST ADVISORY

A Rutgers Cooperative Extension Publication

Effective Treatment of Manganese Deficiency in Soybean Begins with Diagnosing the Problem

Joseph Heckman, Ph.D., Specialist in Soil Fertility

anganese (Mn) deficiency is a widespread problem on sandy Atlantic Coastal Plain soils. It is rare, however, on fine textured soils in Northern New Jersey. The deficiency is especially common in soybean production, but Mn deficiency also occurs on other field crops, vegetables, and even Christmas trees. Over the last two decades I have conducted numerous field trials to determine best agronomic practices for correcting Mn deficiency. This article is part 1 of a series that will summarize the results from my investigations along with the research findings of other scientists. This extension program was funded in part by the New Jersey Soybean Board. One of the reasons why Mn deficiency remains so prevalent is that the problem is not easily corrected in the long term by simply applying micronutrient fertilizer to the soil. While applications of copper (Cu) or zinc (Zn) fertilizer to deficient soils can prevent the reoccurrence of these micronutrient problems for many years, this is not the case for Mn deficiency. One of the reasons why Mn fertilizer has such a short-term availability is that when soil applied, soil microorganisms oxidize most of the Mn to an unavailable form. Identifying fields likely to be Mn deficient before crops are planted is a good place to begin dealing with the problem of Mn deficiency. Knowing that Mn deficiency tends to reoccur in the same fields year after year means that crop and field records are useful for predicting where Mn deficiency is likely to occur in the current growing season. If you observed deficiency symptoms, described as interveinal chlorosis or yellowing between the leaf veins, in last years' crop, in a particular field area, you should anticipate the return of these symptoms. View the photos linked with this article to become familiar with visual symptoms of Mn deficiency. The symptom of interveinal chlorosis is typical of most, but not all crops exhibiting Mn deficiency. Deficiency symptoms for iron and magnesium may appear similar to Mn deficiency. However, deficiencies of these other nutrients in New Jersey are much less common. Except for crops such as blueberry, rhododendron, and azalea, iron deficiency is rare in New Jersey. Thus,

See Mn Deficiency on page 2

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Mn Deficient Tomato on RightMn Fertilized Leaf on Left

INSIDE

Effective Treatment of Mn Deficiency in Soybean Begins with Diagnosing the Problem ................................. 1 Pest Notes .................................... 2 Vegetable IPM Update .............. 3 Weekly Weather Summary ....... 3

Vol. 16 No. 6

Page 1

Pest Notes

Gerald M. Ghidiu, Ph.D., Specialist in Vegetable Entomology Asparagus - Asparagus beetles are still emerging in high numbers and attacking asparagus plants, feeding and depositing eggs on spears. Carbaryl, methomyl and permethrin are effective in controlling asparagus beetles, but newly emerged beetles continue to invade the field and make it appear that insecticide treatments are not working. With the current hot weather and bright sunlight, frequent applications may be necessary to keep the beetle population at a minimum. Wait for 1-2 days after each application, walk the fields and closely monitor population levels. Daily harvest will help minimize the exposure of emerging spears to the beetles and thus reduce damage. Cabbage and related crops - Flea beetles are starting to build up in cole crops. These pests will chew small holes in the leaves, but if populations are high, can cause serious damage especially to young plants. The recommended treatment level is one beetle per plant at transplant, or one beetle per every two plants at the cotyledon stage of plant development. (Long Island recommends treatment be initiated when there is one beetle per plant at this stage). Many materials are labeled for this pest, pre-plant, at-plant, and post-plant. The key is keeping the population from reaching a damaging level. Also, the white butterflies fluttering around the fields are the adult of the imported cabbageworm, a caterpillar that feeds on all of the cole crops. With the current warm temperatures, expect to see this pest on young cabbage leaves. Many materials are labeled and are very effective against this pest, including biological insecticides, and there is no suspected insecticide resistance with imported cabbageworm to any of the listed materials. Coverage of the plant foliage is important, so make sure the nozzles of the sprayer are directed to the upper and lower leaf surfaces. Peas - With the warm weather, monitor pea fields closely for pea aphid populations. These pests feed on all of the plant parts, including stems, leaves, blossoms, and even young pea pods, causing foliage to curl downward and eventually dry out and turn brown. Several materials are available, including acetamiprid, dimethoate, imidacloprid and methomyl. Apply treatment when there are 5-10 aphids per plant or 50 or more aphids per sweep of a 15-inch sweep net. Peas are most susceptible to damage during flowering and pod-fill, and close monitoring of the field for pea aphids during this time are recommended. CORRECTION: Please note that abamectin, Insecticide MOA #6, has been listed twice in Table E-9A of the 2010 Commercial Vegetable Production Recommendations for NJ (page E32). The very first listing is

Page 2

MN Deficiency from page 1

for field crops and vegetables growing in New Jersey, you can generally rule out iron deficiency. Magnesium deficiency is not common, but may occur on soils that have not been properly limed. Soil testing by the Mehlich-3 method is useful for identifying Mn deficient soils. To interpret a soil test for Mn availability, it is necessary to consider both the soil test Mn level and the soil pH because Mn availability is very strongly influenced by pH. Manganese availability decreases as soil pH increases. Soil test interpretations are given in Rutgers Fact Sheet FS 973 Manganese: Needs of Soils and Crops in New Jersey www.rcre.rutgers.edu/pubs/publication.asp?pid=FS973

Mn Deficient Cucurbit on RightMn Fertilized Leaf on Left

Mn Deficient Soybean on RightMn Fertilized Leaf on Left

correct, but the second listing after acephate is incorrect, and should read `acetamiprid, MOA# 4A". All of the vegetable listings are correct for these two materials, only the insecticide for acetamiprid wrongly lists `abamectin'.

Vol. 16 No. 6

Vegetable IPM Update

Kristian Holmstrom, Research Project Coordinator II, Vegetable IPM Program Sweet Corn

As of this week, a few European corn borer (ECB) adults have been captured in the southern counties. These individuals are approximately 2 weeks earlier than the first catches last season, and are the result of the warm weather over the past month. It is probable that the first ECB flight will be earlier than normal all over the state this season, although we would expect the overall trend toward lower ECB numbers to continue. The highest nightly ECB catches for the previous week are as follows: Folsom 1 Hammonton 1 Indian Mills 1 Seeley Lake 1

cides, as well as the predatory mites Neoseiulus fallacis and Phytoseiulus persimillis. The former being more tolerant of temperatures in the upper 80's (F) than the latter. If predatory mites are to be used, they should be purchased immediately upon discovery of TSSM in the tunnel. They typically are shipped in vials of corn grit. The grit should be sprinkled on plants throughout the tunnel, with more applied in areas where TSSM have been found. Predatory mites are available from a number of beneficial insect suppliers. The key is to treat with miticides, or release predators before TSSM gets well established. Once this happens, repeated miticide applications may be necessary to gain adequate control. See the 2010 Commercial Vegetable Production Recommendations for labeled materials.

Cole Crops

Egg laying by imported cabbage butterflies (ICW) is occurring at this time, and will continue as warm weather permits their activity. Scout plantings weekly, paying particular attention to the innermost leaves where ICW often feed. Consider treating if caterpillars are found on 10% or more plants that are in the 0-9 true leaf stage. From 9-leaf to the early head stage (in broccoli, cauliflower and cabbage) infestations up to 20% may be tolerated. Once heads begin to form, a 5% threshold should be observed to protect the marketable portion of the plant. For leafy greens such as collards and kale, 10% plants infested is the threshold throughout. Crucifer flea beetle continues to be active on many plantings (see last week's newsletter). Be sure to monitor newly emerged or transplanted fields for the presence of this pest.

Tomatoes

High tunnel tomato crops have been planted and are becoming established in the northern counties. As of late last week, two-spotted spider mites (TSSM) have been found in one location in Hunterdon County. Because the weather has been warm, early TSSM infestations are more likely. Check 5 consecutive plants each in 5 random locations within the tunnel. Look for whitish "pin-spots" on the upper leaf surfaces. Turn these leaves over and you may find individual TSSM. It is important to treat this pest before it becomes widespread in the tunnel. There are several effective miti-

Weekly Weather Summary

Keith Arnesen, Ph.D., Agricultural Meteorologist

emperatures averaged above normal, averaging 58 degrees north, 60 degrees central and 60 degrees south. Extremes were 94 degrees at Hammonton on the 2nd, and 32 degrees at Newton on the 29th. Weekly rainfall averaged 1.27 inches north, 0.66 inches central, and 0.28 inches south. The heaviest 24 hour total reported was 1.47 inches at Canoe Brook on the 2nd to 3rd. Estimated soil moisture, in percent of field capacity, this past week averaged 96 percent north, 92 percent central and 89 percent south. Four inch soil temperatures averaged 55 degrees north, 57 degrees central and 57 degrees south. Weather Summary for the Week Ending 8 am Monday 5/ 3/10 RAINFALL TEMPERATURE GDD BASE50 MON WEATHER STATIONS WEEK TOTAL DEP MX MN AVG DEP TOT DEP %FC BELVIDERE BRIDGE 1.05 10.16 2.01 87 34 57. 1 197 146 98 CANOE BROOK 2.00 16.48 7.52 93 34 60. 5 289 249 100 CHARLOTTEBURG .96 16.07 7.25 89 34 57. 4 212 200 87 FLEMINGTON 1.74 13.98 5.40 92 37 60. 5 263 218 100 NEWTON .62 11.68 3.82 88 32 56. 2 200 178 89 FREEHOLD .79 12.80 4.31 90 35 61. 4 312 242 87 LONG BRANCH .80 13.32 4.54 90 37 59. 3 217 162 78 NEW BRUNSWICK .75 13.75 5.56 93 33 61. 4 289 200 90 TOMS RIVER .46 11.89 3.31 93 34 60. 4 256 195 71 TRENTON .51 9.92 2.22 91 39 60. 2 331 224 72 CAPE MAY COURT HOUSE .12 10.33 2.86 87 35 57. 0 219 129 76 DOWNSTOWN .19 9.82 2.12 92 33 60. 1 295 181 76 GLASSBORO 1.04 11.44 3.31 88 41 59. 1 334 227 92 HAMMONTON .23 10.46 2.56 94 38 61. 3 340 238 69 POMONA .04 10.12 2.59 91 36 62. 5 299 225 69 SEABROOK .06 9.70 2.81 88 37 63. 4 376 259 71 SOUTH HARRISON * .78 8.88 1.48 88 41 61 NA 340 NA NA WES KLINE -- GDD BASE 40 PINEY HOLLOW LAST WEEK 99 (ENDING 4/26/10) THIS WEEK 140 (Ending 5/3/10)

Vol. 16 No. 6 Page 3

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PLANT & PEST ADVISORY

VEGETABLE CROPS EDITION CONTRIBUTORS

Rutgers NJAES Cooperative Extension Specialists Gerald M. Ghidiu, Ph.D., Vegetable Entomology George Hamilton, Ph.D., Pest Management Joseph R. Heckman, Ph.D., Soil Fertility Bradley A. Majek, Ph.D., Weed Science Andy Wyenandt, Ph.D., Vegetable Pathology Rutgers NJAES-CE County Agricultural Agents Atlantic, Richard W. VanVranken (609-625-0056) Burlington, Raymond J. Samulis (609-265-5050) Cape May, Jenny Carleo (609-465-5115) Cumberland, Wesley Kline, Ph.D. (856-451-2800) Gloucester, Michelle Infante-Casella (856-307-6450) Hunterdon, Winfred P. Cowgill, Jr. (908-788-1338) Middlesex, William T. Hlubik (732-398-5260) Monmouth, Bill Sciarappa, Ph.D. (732-431-7260) Morris, Peter J. Nitzsche (973-285-8300) Passaic, Elaine F. Barbour, Agric. Assistant (973-305-5740) Salem (856-769-0090) Warren, William H. Tietjen (908-475-6505) Vegetable IPM Program (732-932-9802) Joseph Ingerson-Mahar, Vegetable IPM Coordinator Kristian E. Holmstrom, Research Project Coordinator II Newsletter Production Jack Rabin, Associate Director for Farm Services, NJAES Cindy Rovins, Agricultural Communications Editor

Pesticide User Responsibility: Use pesticides safely and follow instructions on labels. The pesticide user is reponsible for proper use, storage and disposal, residues on crops, and damage caused by drift. For specific labels, special local-needs label 24(c) registration, or section 18 exemption, contact RCE in your County. Use of Trade Names: No discrimination or endorsement is intended in the use of trade names in this publication. In some instances a compound may be sold under different trade names and may vary as to label clearances. Reproduction of Articles: RCE invites reproduction of individual articles, source cited with complete article name, author name, followed by Rutgers Cooperative Extension, Plant & Pest Advisory Newsletter. The Vegetable Crops On-Line Resource Center website is a dedicated source for information on production, insect, weed and disease management, food safety, marketing and more: www.njveg.rutgers.edu

For back issues of the Plant & Pest Advisory:

www.rce.rutgers.edu/pubs/plantandpestadvisory

Plant & Pest Advisory Rutgers School of Environmental and Biological Sciences ASB II, 57 US Hwy. 1 New Brunswick, N.J. 08901

MILLTOWN, NJ 08850 FIRST CLASS POSTAGE PAID PERMIT #576

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