Category Archives: Pasture

Leaf Blight & Leaf Rust In Pasture

Tift85Bermuda-Rust-Helminthosporium 002

Here is a Tift 85 pasture that has been cut twice so far and is showing symtpoms down on the leaves and lower down the stem. We are seeing both leaf blight (helminthosproium) and leaf rust. These issues we commonly see in late summer when weather is warm, usually between 75 degrees F and 90 degrees F, and with high relative humidity.

Leaf Blight

Bermudagrass leaf spot is caused by a fungus from the genus Helminthosporium, and the disease has been informally called Helminthosporium leaf spot, Helminthosporium leaf blotch, or Leaf Blight. Leaf lesions of helminthosporium are irregularly shaped and brownish green to black in color. We may see it in irregular patches. Leaf spots are more numerous near the collar of the leaf blade.

Leaf Blight

Leaf Blight

LeafRust

Leaf Rust postules

Leaf Rust

Leaf rust or Puccinia disease has similar impacts as Helminthosporium. We will also see red to orange lesions can on leaf and stem. Look for a raised area or blister which is the rust postules like we see in wheat and corn. Rubbing your finger over the leaf will leave a rusty color.

Management

Management is strictly avoidance. Coastal, Tift 44, and Tift 85 have some level of resistance while Alicia is extremely susceptible. But even less susceptible varieties are infected with leaf spot when potassium is low. Most reported leaf spot cases are directly related to low soil potash. Nutrients are removed from bermuda hay fields in about a 4-1-3 ratio of N, P2O5, and K2O with harvest. We need 75 percent as much potash as nitrogen  applied each season. Split applications of K are better in sandy soils. With helminthosporium, removing the inoculant is also recommended. In addition to tying up nutrients, thatch holds water and reduces air circulation. This is a conducive environment for inoculum. The only practical way to reduce thatch is burning in spring before green-up.

Visit Leafspot Diagnosis and Management in Bermudagrass Forages for more information.

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Controlling Briars

Blackberry (2)

Briars such as blackberry and dewberry are seen in pastures this time of year. UGA Forage Team Memeber and Miller County Agent Brock Ward has come up with some pointers on controlling these weeds:

There are many bramble type weeds that are called blackberries by area forage producers. These weeds often require significant growth before we can tell them apart. The good news is that they generally can be controlled using the same chemistry.

For areas where briars are a problem, control is a matter of herbicide timing. For instance, if spring was the first time a bramble weed was identified, you can wait until late September or mid-October to apply a herbicide. Waiting until fall is preferred because most of the herbicides are systemic and need adequate leaf surface to take in the chemical for translocation. During the Fall, the weeds prepare for overwintering.

Water is also needed for many of our herbicides to affect the plants. Timing application both after and ahead of a rain / irrigation will help ensure the plant is actively growing to maximize efficacy. Applying herbicides to drought stressed weeds can lead to a failure in control. Moisture stress can cause the cuticle on the leaf to harden off which reduces herbicide penetration. Delaying applications until brambles have recovered from drought stress will enhance herbicide absorption and improve efficacy for control. It will also take some time for the herbicides to fully control the weeds. Waiting six to eight weeks before mowing the weeds after application of a herbicide is recommended.

Blackberry

Blackberry

If the weeds have been previously mowed or a mature stand is currently overgrown, the area needs to be evaluated and managed to get herbicide on the actively growing material. In the case where a large mass of weeds have grown for more than two seasons, mow the weeds to get a flush of younger, more susceptible leaf tissue. This can be timed by cutting about six months before applying the chemical. A potential method is to cut in the fall through late winter and treat in the fall of the next year. This allows the foliage to have adequate growth for the herbicide to interact with and get better control.

To help your county agent with the herbicide decision, be prepared to discuss your desired grass or forage and what you are looking to control. Oftentimes there are numerous weed species needing treatment. We may prioritize weeds of greatest concern. In most cases, control of multiple broadleaf species with a single application can occur, but timing is critical.

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Creeping Indigo In Monticello

Jefferson County Agent Jed Dillard came across creeping indigo that he hasn’t seen in Monticello. Much has been discussed by Equine vets at UF since it is TOXIC to livestock. Below is some information from put together by Jed:

Creeping indigo is low growing

Creeping indigo is low growing

The plant is a low growing legume with pink blooms somewhat like clover and small bean like seed pods (attachment 2). Leaves contain seven to nine leaflets, and the prostrate stems creep along the soil surface. The plant can also form mats underneath a healthy pasture canopy as shown in this Creeping Indigo Fact Sheet. This will make it even more difficult to find if it migrates to Panhandle pastures.

Creeping indigo (Indigofera spicata) should not be confused with hairy indigo (Indigofera hirsuta). Hairy indigo can approach waist high, but creeping indigo will barely rise above the toe of your brogans.

Annual lespedeza (Lespedeza striata) (shown in attachment 3, mixed with centipede grass) is similar in appearance, but unrelated and non-toxic. Its prostrate growth habit is similar to creeping indigo, but its leaves are somewhat smaller and have only three leaflets. The stems of the common lespedeza plants I found across the sidewalk were also woodier than the stems of the creeping indigo.

Creeping indigo seed pods

Creeping indigo seed pods

Identification

Identification of any toxic plant is the first step in its control. Next, mechanical control may be a feasible option if the population is small when you find it. If you pull or hoe the plants, make sure you destroy any seeds as well as the plants. Seed can be viable surprisingly early and the stem and leaves remain toxic after they die and dry. The plant has a deep tap root, so mechanical control can be challenging.

Chemical control has not been established, but GrazonNext HL at 24 oz. per acre may be effective as it has good control of other legumes. Remember the dead plants in your pasture are still a threat. Manure from animals grazing treated pastures or hay from treated should not be used for compost.

This plant has been a problem in South and Central Florida and much good information on specifics of toxicity and symptoms.

Information

Creeping Indigo Toxicity – Dr. Rob MacKay

Creeping Indigo: A Small, Yet Lethal Plant – Sellers, Carlisle and Wiggins. South Florida Beef Forage Program.

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Fertility Issues In Pastures

PastureRenovation 002

I’ve looked at a few pastures this week that show signs of fertility and cultural issues. These are horse pastures which were planted in bermudagrass but have been overtaken by centipedegrass. This is very common in pastures that have not been limed over the years. Centipedegrass can withstand a lower pH than bermudagrass. Bermuda likes a pH no lower than 6.0.

I observed another pasture today where bermuda was established but now taken over by bahia and broadleaf weeds. Bahiagrass can also tolerate low pH and fertility. Horses also graze this pasture which results in soil compaction. In this pasture many broadleaf weeds have taken over like serrated ground cherry and chamberbitter. When much of the pasture is struggling to produce, it is recocomended to do a pasture renovation.

Pasture Renovation

The first step in renovation is killing out the current grass species. This is better accomplished in the late summer/early fall with glyphosate. It can then be followed up by another spray, followed by planting a winter grass, like ryegrass. The next spring, that site needs to be cut or grazed real close and then sprig/seed your desired grass. UGA Extension Forage Agronomist Dr. Dennis Hancock has information on the UGA Forages website on specific grass species. (Click on Establishment Guidelines on the left and scroll down.) Here is what Dr. Hancock recommends:

“Renovating an old common bermudagrass stand is very difficult. Even with repeated glyphosate sprays, there will be some survival of old rhizomes. Some tillage in combination with glyphosate sprays with help expose rhizomes and increase percent control. Common bermudagrass can be more completely controlled if the land can be rotated for one to three years to crops where intensive grass control measures can be employed, in addition to using the glyphosate sprays.”

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Summer Pasture Weeds

MaypopPassionflower 002

The last few weeks, we’ve been looking at both grass and broadleaf pasture weeds. These are both fields that are cut for hay. In some fields, we are seeing grasses right now, such as crabgrass, vasseygrass and broadleaf signalgrass. Below is a photo of broadleaf signalgrass, which is a summer annual, wide-bladed grass. This is a weed that is we’d like to control with pre-emergent herbicides, although a few post-emergent herbicides have selectivity for these grass weeds. The selective herbicides are known to yellow Bermuda pastures, and there are certain precautions we can take to reduce yield.

Broadleaf Signalgrass

Broadleaf Signalgrass

MaypopPassionflower 007

Maypop passionflower fruit

In another pasture, we looked at a few broadleaf weeds, one being maypop passionflower. This is a perennial vine that grows along roadsides, fields and pastures. These flowers are just opening, but the petals will be bluish to white with green or yellow berry. The leaves are alternate with 3 lobes. In this pasture, we’ll have options of post-emergent herbicides that have activity on this weed.

For any of these type of summer pasture weeds, discuss control options with your Extension Agent.

Maypop Passionflower

Maypop Passionflower

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Pasture Renovation

PastureRenovation 009

We’ll get calls about pastures that have been taken over by centipedegrass which is not suited as a forage for animals to graze. These pastures need to undergo renovation and re-establish a good forage variety. Centipedegrass can withstand a lower pH than bermudagrass – usually in the low 5’s. When we see pastures taken over by centipede, it usually means the pasture has not been limed in some time.

The first step in renovation is killing out the current grass species. This is better accomplished in the late summer/early fall with glyphosate. It can then be followed up by another spray, followed by planting a winter grass, like ryegrass. The next spring, that site needs to be cut or grazed real close and then sprig/seed your desired grass. UGA Extension Forage Agronomist Dr. Dennis Hancock has information on the UGA Forages website on specific grass species. (Click on Establishment Guidelines on the left and scroll down.) Here is what he says about centipede:

“Renovating an old common bermudagrass stand is very difficult. Even with repeated glyphosate sprays, there will be some survival of old rhizomes. Some tillage in combination with glyphosate sprays with help expose rhizomes and increase percent control. Common bermudagrass can be more completely controlled if the land can be rotated for one to three years to crops where intensive grass control measures can be employed, in addition to using the glyphosate sprays.”

I took a soil sample of this pasture above, and you can see how low the pH has dropped.

PastureRennovation

 

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Thistle & Dogfennel Control Timing

Weeds are pests year round in pastures and hayfields. It is a struggle staying ahead of weeds with such a broadspectrum of species. Here is information by Miller County Ag Agent Brock Ward on two of the most common weed problems in Georgia:

Thistle

First we will start with the thistle complex as it is often overlooked during the best time for control. Starting in mid-January through mid-March, producers should scout for the presence of thistles in the rosette stage of growth. This is the stage of growth where the plant is low to the ground and grows outward from its taproot as a mass of leaves just above the soil surface. It is easy to drive by a hayfield or pasture and not even suspect the presence of thistles.  The thistle complex consists of several different species but they are all treated as one complex.

Timing is the most critical element in the management. When in the rosette stage, chemical control of thistle is much better than if the plants are bolting, or growing taller from the center. Also it is even harder to kill a thistle once it has begun to flower. It is beneficial to attack thistles during the rosette stage as it is susceptible to a broader range of cost effective herbicides.

Thistle Photo by Brock Ward

Thistle Photo by Brock Ward

Dogfennel

Dogfennel is also a weed that has substantial economic importance. Dogfennel can spread from its root stock causing larger groups that shade the desired forage and reducing yields. It is particularly troublesome in overgrazed pastures or areas where pH has drifted below desired levels for most grasses. Although dormant during the winter months, growth resumes and seed germinates as early as April and can grow to sizes that shade desirable forages in a few months.

Although they are easier to scout than thistles, dogfennel requires the same timely approach for adequate control. When less than 20 inches tall, dogfennels are much easier to control and producers have a broader range of herbicides from which to choose. After they exceed 20 inches in height, some of the more cost effective herbicides become less effective and a more costly herbicide may need to be used for adequate control.

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Armyworms In Hayfields

Armyworms025

Armyworms026Fall armyworms are in our hayfields now. This is a Bermuda hayfield that is down to the stems. You can see the damage has caused the pasture to look dry with a silver tint. The foliage feeding caterpillars are also feeding on other grasses like this vasseygrass. Just last week, this field was getting close to being cut. The caterpillars move very fast and can do the damage in just a few days. Here is a link to the 2014 UGA Pest Control Handbook Pasture Section.

 

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Watch Out For Stinging Nettle

Nettle

If you have ever touched a stinging nettle, you would know it. One got me for the first time last year. I was looking for a wasp after I was stung it hurt so bad. I’ve been getting reports of some stinging weeds in pastures this past week. We looked at a pasture last week where this weed (above) was in pastures and horses got into it. Not all plants of this species sting, but in this picture you can almost see some of the stinging hairs called trichomes. This nettle was growing close to the ground. They are commonly seen along fence rows growing taller. UGA Extension Forage Weed Scientist, Dr. Patrick McCullough, said this photo this is a young stinging nettle plant or closely related species. Weed control options include anything with picloram (Grazon P + D) or aminopyralid (Milestone, Surmount).

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