NFREC NEWS

From the Director: Our goal is to provide the faculty with the latest news from the Center research projects and extension activities, and other timely information items. Please feel free to use the contents of the newsletter in your county newsletters and education activities as you wish. If you'd like additional details on newsletter items, contact the faculty member author or our editor, Cheryl Vergot.
Regards, Dr. George Hochmuth, NFREC Director

                                                               April 20: Bale Haylage Field Day
                                                                                     W. B. Edwards Farm, Lloyd, FL
                                                                     (by Jefferson Co. Extension Office 850-342-0187)

Dr. David Zimet, NFREC-Quincy, was recently elected Vice Chair of the Florida State Rural Development Council.

Newsflash: Pawel & Megumi Wiatrak became proud parents on April 13 as their firstborn child entered the world. Sara Arai was born about 7:30 a.m. and weighed in at 6 lb. 8oz. Pawel & Megumi (Pawel works for Dr. David Wright at NFREC-Quincy) said that the baby card, good wishes and contributions from fellow employees are greatly appreciated!

Welcome to Lynn Wells, new accountant at NFREC-Quincy. We're glad to meet you!!

Nitrate toxicity in animals is related to the type of digestive system. Nonruminants have a low pH (high acidity) in their digestive system that inhibits growth of bacteria that convert nitrate (NO3-) to the toxic nitrite (NO2-). The rumen of cattle (caecum of horses) is designed to digest fibrous material, it contains special bacteria, and is slightly acid to neutral so that bacteria that convert nitrate to nitrite thrive.

Nitrites reduce oxygen-carrying capacity of blood and death is likely after 70% of the hemoglobin is converted to methemoglobin. Nitrates at levels below the lethal dosage reduces growth or milk production which is more likely due to reduced palatability and feed intake than to direct toxicity.

Livestock have considerable capacity to adapt to continuous intake of nitrates and when they are conditioned over a period of weeks the amount tolerated increases. Nitrates in water are much more toxic than in feed and carbohydrates in the diet reduce effects of nitrates.

The lethal dosage range of nitrates for cattle is 75 to 140 Mg of nitrogen per kilogram of body weight or 34 to 63 grams of nitrogen in the nitrate form for a 1000 lb animal.

Minimum lethal dosage is based on 75 milligrams (mg) of Nitrogen (N) per kilogram (kg) of body weight of cattle. This is equal to 34 grams (34000 mg) of nitrogen per 1000 lb animal. ppm = milligrams per kilogram. ppm N = 0.226 x ppm nitrate. Minimum lethal dosage of forage containing 7000 ppm nitrate or 1582 ppm N = (34000 mg of N per 1000 lb cow /1582 mg of N per kg of forage) x 2.2 lb/kg = 47.3 lb of forage per 1000 lb cow.

Causes of Nitrate Build-up in Grain and Forage Crops
1. High N supply such as fertilizer N, legumes, manure, or organic matter.
2. High plant population or drouth can cause barren stalks in corn resulting in less grain for conversion of nitrate to protein.
3. Cloudy weather, less sunlight limits nitrate reductase activity which slows conversion of nitrate to plant N compounds.
4. Acute shortage of nutrients other than N.
5. Rain following an extended dry period causes temporary build-up of nitrate which will decrease as plants start to grow following recovery from stress due to lack of water.

Tests for Nitrate Levels in Grain
and Forage Crops
1. Diphenylamine: a colorimetric method. A drop of the chemical on cut plant tissue will produce a dark blue color if nitrates are present in high concentration. Tissue turns brown in the absence of nitrates.
2 Cardy Meter: a portable nitrate ion meter. Quantitatively measures nitrate ion concentration. This method offers a quick moderately accurate measure of nitrates in forages.
3. For high accuracy, samples can be sent to a
university or commercial laboratory.

The nitrate ion meter is accurate enough for determining safety of nitrate containing feeds if one is careful to err on the low side of the toxicity range. Following is a suggested procedure for operation of the Cardy Nitrate Meter to measure nitrate-N in forage.
Use standard solutions to calibrate. Always calibrate with highest standard first. Place two or three drops to connect the two dots on the sensor surface. Allow to stand for 30 to 45 seconds before taking a reading. If meter has been out of use for several weeks it may take several tries to calibrate with both solutions by alternating each until reading comes back to specified level without adjusting calibration buttons for each solution.
To determine nitrate level of forage: place 200 mL of water in kitchen blender add 10 grams of forage. Place on liquify setting until finely chopped, place two or three drops of resulting liquid on nitrate meter sensor and take reading in ppm nitrate ions, multiply by 20 to get concentration in forage, then multiply by 0.226 to obtain forage concentration of nitrate-N.

FEEDING PRACTICES FOR HIGH NITRATE FORAGES TO REDUCE POTENTIAL TOXICITY
1. Feed animals hay, grain, and protein supplements before turning into pasture or field with high nitrate forages.

2. Convert high-nitrate forages to silage rather than green feeding. From 20 to 50 percent of nitrates will disappear after a few weeks in the silo, however, "silogas" may be a problem.

3. Let crop mature more than usual, since nitrates normally decline as plants get older. Use a quick test to determine when nitrates have declined.

4. Cut corn, millet, etc. at 18 to 24 inches high, this will leave the stalk portion having the highest nitrate content in the field.

5. Feed high-energy low-nitrate materials such as grain along with silage to dilute nitrate content.

6. Check your water supply to make sure it is not contributing to the nitrate problem.

7. Small amounts of high-nitrate silage fed two or three times per day rather than all at once enable cattle to tolerate nitrates better.

8. Start feeding high-nitrate silage as a small portion of the daily feed intake and gradually increase as the animals develop nitrate tolerance. Check nitrate content of high-nitrate forages to determine how much is required to supply a lethal dose and keep forage intake below this level. (Rhoads, NFREC News, 2-08)

Cotton Nematode Management (Bob Kinloch and Jim Rich):
The Cotton Nematode Management Guide has been recently expanded and updated. A table was added listing rotation crop recommendations for each of the three major cotton nematode pests (root-knot, reniform, sting). Nematicide recommendations were revised as well after extensive tests conducted in Quincy and Jay over the past four years. Temik 15G is now only recommended at the 7 lbs./A rate for nematode suppression, lower rates did not perform well or not at all in our trials. Telone II remains the nematicide of choice to control nematodes in fields heavily infested with nematodes. Reniform and sting nematodes are managed well when using a single in-row chisel application of Telone II at 3 gals./A. In fields heavily infested with the Southern root-knot nematode, economically viable yield responses were found up to the 6 gals./A rate.
For further details, please contact us or you can find the revised Guide at <http://edis.ifas.ufl.edu/NFREC5>.
(Rich, NFREC News, 2-08)

Ornamental Grass Evaluation Gardens Established

Ornamental grass evaluation and demonstration gardens were established in late January this year at the Leon County Cooperative Extension Service in Tallahassee (pictured below) and at the West Florida Research & Education Center in Milton. The same 30 grass species or cultivars(native and nonnative; about 50% of each) have been planted at each site.The grasses will be evaluated over a 3-year period so as to obtain a good idea of their performance under a variety of weather conditions. There are six plants of each entry arranged in manner that will allow a valid statistical analysis of the data.

Plants are being grown under low maintenance conditions. Supplementary irrigation was used for the first few weeks at the Leon County site to aid in establishment but will not be used again except in the case of an extended drought. Weeds will be controlled mainly by hand weeding and mulch (shredded tree trimmings from the City of Tallahassee laid over landscape fabric). Glyphosate will be used to control weeds around the fence and for severe weed infestations in the aisles. The only other pesticides used will be for fireant control.

These evaluations are a cooperative effort among Mack Thetford (West Florida REC), Jeff Norcini (North Florida REC), and Will Sheftall, David Marshall, Geoff Brown, Master Gardeners, and Master Wildlife Conservationists of the Leon County Cooperative Extension Service.

Field Days highlighting first year results will be held Tuesday, October 3 in Leon County and on Thursday, October 5 in Milton.

To gain access to the gardens, contact Will Sheftall, David Marshall, or Geoff Brown at the Leon County Cooperative Extension Service, and Mack Thetford at the West Florida REC. (Norcini, NFREC News, 2-08)

Cheryl Vergot, Public Relations
NFREC - Quincy, U/F IFAS
E-Mail: cvergot@ifas.ufl.edu
Phone: (850) 875-7112

The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, age handicap or national origin.

COOPERATIVE EXTENSION WORK IN AGRICULTURE, FAMILY & CONSUMER SERVICES, STATE OF FLORIDA, IFAS, UNIVERSITY OF FLORIDA, U.S. DEPARTMENT OF AGRICULTURE, AND BOARDS OF COUNTY COMMISSIONER COOPERATING