August 2017 Newsletter - #67
 
 
In This Issue
About Us
The Dairy One Forage Lab excels in providing high quality analyses  
and customer service. Our goal is to provide analytical services designed to meet the expanding demands of modern agriculture.  
New technology and traditional methods are combined to deliver fast, accurate results.
 
New blights and bugs due to rains 
Sarah Fessenden, Forage Tech Support and Sales Specialist

Beyond the yield drag and quality loss due to a wet growing season, we are also seeing increased insect damage and blights. Corn is suffering from common blights and pests that accompany a wet year, while alfalfa is seeing a few uncommon diseases.

Corn diseases
Grey leaf sp ot prefers wet humid weather, making this growing season a perfect climate for it. It is caused by Cercospora zeaemaydis, a fungus. No-till and reduced-till corn is particularly susceptible as the spores are spread through corn debris. Fungicides can be used to prevent loss during the season and crop rotation is helpful when tillage isn't an option. 
 
Northern corn leaf spot is also more prevalent in no-till fields. Caused by Cochliobolus carbonum, it also thrives in high humidity and warm weather. To thwart development, use resistant hybrids. The spores overwinter in crop debris, so utilize tillage and crop rotation to help manage the disease.

Eyespot can be managed through use of resistant hybrids, tillage, and crop rotations. It is caused by Kabatiella zeae, and spores can be spread long distance through wind.



Common corn rust  is caused by Puccinia sorghi. Plant early and use resistant hybrids to manage the rust. It survives over the winter in the south and airborne spores move to northern states in growing season.


Anthracnose leaf blight can be prevented by using resistant hybrids and tillage. The spores overwinter in plant residue and where tillage is not an option, crop rotations can help manage this disease. Caused by Colletotrichum graminicola, it affects lower leaves early in the growing season and the upper leaves later on.

Alfalfa diseases
 
Potato leafhopper
is typically not an issue in New York, it tends to effect Pennsylvania and southern states. Due to the early season storms from the Gulf, we have seen several infestations. The insect decreases yield and quality and increases root rot. The bugs are picked up in low-pressure systems where they ride the storm and are deposited in fields in down drafts. Eggs are deposited on the stems and leaves as the females land in the fields. Most of the damage to the crop will be in the second and subsequent cuttings.

Other alfalfa diseases can target the root, crown, or stem. If you see yellowing, stunting, or premature plant death, it is likely caused by a rot that interferes with water and nutrient uptake. Phytophthora root rot is common in a wet season and sclerotinia crown and stem rot is common with reduced tillage.

 

Mold and Yeast
Mold spores can be present in soil or plant debris with the potential to grow in the field or in storage. Favorable conditions for mold growth are a silage temperature range of 50 - 104 degrees fahrenheit and a pH range of 4-8. The presence of mold does not directly indicate the presence or absence of mycotoxins. Additionally, molds can cause a decrease in animal performance whether or not mycotoxins are produced.

The major effects of mycotoxins on cows are:
  • Increased stress
  • Reduced feed intake
  • Reduced nutrient absorption
  • Nutrient metabolism blocked or altered
  • Antibiotic effect on rumen microflora
  • Suppression of immunity
  • Cellular death with different target tissues
  • Systemic toxicity
Mycotoxins can also lead to mycosis, mycotic abortions, and many other health events as well as decreased cow performance.

Yeast mainly affects corn silage, high moisture corn, and earlage/snaplage. Yeast production is favorable when there is a cool growing season with a late harvest. These conditions are unfavorable for bacteria species that help with fermentation and preservation of ensiled feeds. A high yeast count usually results in heating of silages followed by the growing of additional mold. The unstable silages result in nutrient loss and typically decreased dry matter intake.

The mechanism of yeast and aerobic instability is depicted below:
  • High endemic yeast population is ensiled
  • During slow fermentations, moderate growth of yeast occurs until oxygen is expired in the silage
  • At feed-out, yeasts are re-exposed to oxygen
  • Yeast growth becomes exponential
  • Lactic acid is consumed
  • Heating occurs
  • Silage acids are volatized
  • Silage pH rises
  • Molds with low oxygen requirements (Mucor) invade the silage
  • Aerobic instability
Keep an eye out for our new mold and yeast interpretation sheet with helpful charts for interpreting results. Please contact us with any questions.
Check your chop!

With corn silage harvest coming up, it is important to take your time and make sure you put up the best feed that you can. Dairy One offers Corn Silage Processing Score (CSPS) testing. CSPS is determined by drying ~160 grams of a corn silage sample and shaking the dried sample for 10 minutes on a series of sieves.

The percentage of starch that passes through the coarse sieves (particles < 4.75 mm) represent the adequately processed kernels. The percentage of starch passing through the 4.75 mm sieve is determined by subtracting the amount of starch that did not pass through the 4.75 mm sieve from the total starch in the sample. The percentage of starch that passed through the 4.75 mm sieve is the CSPS. The guidelines for interpreting the results are:
  • Greater than 70% - Optimum
  • 50 - 70% - Adequate
  • Less than 50% - Inadequately Processed
The concept is similar to that of the Penn State Shaker Box in an attempt to quantify particle size distribution. Properly processed silage should achieve a balance between coarse particles to stimulate chewing and rumination and fine particles to enhance digestibility. The CSPS specifically targets starch. Starch in the coarse fraction will be less digested than that in the fine. Lower CSPS scores associated with starch in the coarse fraction can result in an increase of fecal starch. Studies from VitaPlus and Dr. Jim Ferguson at the University of Pennsylvania show that a decreasing fecal starch can result in increased milk production. In contrast, fine particles passing through a 1.18 mm sieve are more readily digestible, but rapid fermentation may cause problems when rations low in effective fiber are fed.

Use the CSPS to ensure that the kernels in your silage are properly processed to promote starch digestibility and enhance the feeding value of your silage.
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Dairy One - Forage Laboratory
730 Warren Road ~ Ithaca, NY ~ 14850
Phone:  1-800-344-2697 Ext. 9962