Monthly Archives: January 2015

Herbicide Considerations On Newly Planted Pines

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We were out looking at longleaf pine seedlings established on a plantation south of town. They have just planted around 12,000 longleaf pines. They are planting at 720 trees per acre. The trees are placed 6 freet from one another and rows are 10 feet apart. This will allow space for mowing for weed control. Also note that the plug is a little out of the soil. This is to keep soil from covering that terminal bud. We don’t want to be too much out of the soil for concerns of losing water either. Once the trees are established, then weed control options will be considered.

Longleaf-DerrickO.-Entomosporium 002Not only do we need to follow the herbicide label and use recommended herbicides at seedling stage, we need to watch closely about our timing. We need to wait at least two months to apply herbicide over the top of long leaf and slash pines (2 inches of white feeder root  growth from 5 laterals), and one month for loblolly. Here are some thoughts on applying herbicides to newly planted pines for herbaceous weed control from UGA Extension Forester Dr. David Moorhead:

  • Be sure that the planted seedlings have started active root growth before herbicides are applied. Dig several seedling up and check for root growth into the surrounding soil. Cold temperature, dry soils or excessively wet soils can delay the start of new root growth. These photos (below) show root plugs of containerized longleaf seedlings. The plug on the left is a newly planted plug where root growth has not emerged from the plug. On the right, the seedling has active root growth into the surrounding soil – at this point it is safe to apply herbaceous weed control. With bareroot seedlings new roots should also be growing into the surrounding soil.
Photo by Dr. David Moorhead-UGA

Photo by Dr. David Moorhead-UGA

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Filed under Forestry, Weed Science

Sidedressing Considerations

Our wheat is in the tillering stage, and now is time to sidedress. Wheat needs between 100 and 130 lbs of N in a growing season. We do not put all N out in the fall because we do not want plants to grow too much which will injury head during cold weather. The demand for N is low during the fall but increased just before stem elongation. We wait until January and February to put out most of our N before stem elongation. We put out recommended N at planting then finish our total N during side dressing. We count tillers and determine if we sidedress one or two times.

These tillers are like multiple stems that will each have a head. More tillers equals give us more grain heads which means more kernels and higher yield. Below is a picture of the tillers on this plant.

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Wheat tillers

 

If wheat is drilled (usually 7.5 inch rows) then 19 feet of the row would equal a square foot. This field was broadcast, so I just checked random square foot spots. I count all tillers on the plants within that square foot. If we do not have 100 tillers per square foot, then we split side dress applications to the last week of January and the next application the second week of February.  If we have 100 or so tillers per square foot and good growth and don’t see much yellowing of the older foliage, we can wait until the 2nd week of February to put out all of our sidedress fertilizer.

Below is a picture of nitrogen deficient leaves. Since N is mobile in the plant, the lower leaves will turn yellow first. N and K are mobile in the soil also and will leach with rains.

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Nitrogen deficient leaves of wheat

 

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Filed under Fertility, Grain

Aphids Present In Wheat

I checked a small grain field yesterday afternoon and was noticing abundance of aphids. They were hit or miss a few week ago, but I am now seeing aphids each spot I stop in the field. Aphids are soft-bodied insects in the “true bug” family (Hemiptera) which means they have piercing-sucking mouthparts. They suck juice from the plant but are also disease transmitters. Barley yellow dwarf virus is a disease they vector. Wheat can be damaged but oats are more susceptible. BYD is present in most fields throughout GA and yield losses of 5-15% are common. Yield losses are greatest when plants are infected as seedlings.

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Wheat is tillering good now and standing 6-10 inches tall. At this growth stage, our threshold is 6 aphids per row foot. The field I was in was broadcasted, so its more difficult to count. At every location I checked, I was seeing 1 or 2 aphids on a plant. Since this field is at threshold, should be treated. The aphids I found were bird cherry-oat aphids, which UGA Extension Grain Entomologist Dr. David Buntin says is the main species that transmits BYD virus in the winter. A  lambda cyhalothrin pyrethroid such as Karate or similar product is recommended to treat for these aphids.

Bird Cherry-Oat Aphid

Bird Cherry-Oat Aphid

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Filed under Entomology, Grain

Late Soybean Harvesting

BenStringer-Soybeans 001

Here are some soybeans down below Metcalf that were not able to be harvested since a creek washed out the road leading to these back fields. We wondered about aflatoxin issues but UGA Extension Pathologist Dr. Bob Kemerait says this is generally not an issue with soybeans. Because of the wet and dry conditions soybeans went through, the issue is going to be quality. UGA Extension Soybean Agronomist Dr. Jared Whitaker says this shriveling is a sign the beans have went through periods of wet and dry conditions. There is some mold is on the grain but not an issue. These beans are to be sold, so it maybe best to take some to the buyer and let them make an assessment. The quality is not as bad as we thought and would probably be some deduction when bought.

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Filed under Soybeans, Weather

Cold On Small Grain

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Cabbage-Frost 011Here is some wheat from last week that was showing some cold burn on the leaves. We got down to 21 degrees on Jan 8th. This burn will not be a problem in wheat since we are so early in growth stage and heads have not emerged. The main issue is slowing down growth. With forage crops, cold duration can hurt us since we are so slow in establishing our forage.  Seminole County Agent Rome Ethredge talked about leaves farthest from the ground have the worst damage. This is because water has a high specific heat, therefore moist soils will hold heat better. We may also see more damage where soils are dry for this same reason.

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Filed under Grain

Floridan Aquifer levels in Southwest Georgia – 2014

Seminole Crop E News

What about our aquifer that we irrigated so much from this summer? It allowed us to make good yields on land a few feet from where crops were not harvested due to dry weather.

Well, the Floridan aquifer was well recharged going into the summer drought. This chart shows the whole year of 2014 in terms of well water levels. You can see how the level (blue line for 2014) dropped, but not much below average levels(gold triangles). Then our rains starting in early September have recharged the aquifer nicely again.

Today, it’s 23 feet down to water in this Miller county test well, which is about 8 feet better than normal for this time of year.

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Managing Ambrosia Beetles In Pecans

Ambrosia Beetles

Ambrosia Beetles

Early last season we looked at a young pecan orchard hit with ambrosia beetles. They are evident by the “toothpicks” of boring dust pushing out of the tree. UGA Extension Entomologist Dr Will Hudson says there is not preventative management of these beetles. They are also hard to know where they will attack since the species of ambrosia beetles also attacks woody tree species. They are essentially everywhere.

The one thing growers can do to limit losses is trap adult beetles to pin point when the first flight originates. This has been highly variable in past studies, ranging from late January to mid-March in south GA.  We never found any way to predict a date, so we settled on beginning trapping by February 1st as the best plan.

Trap Design

There are several traps that work (Google “ambrosia beetle traps”), but the simplest and most efficient is made from a bolt of wood with a hole drilled down the center.  Any hardwood will work, and a branch 2” – 4” in diameter about 2 feet long will do the trick. Drill a ½” (+/-) diameter hole down the center as far as you can (but not all the way through) and fill it with ethanol (grain alcohol, not rubbing alcohol; denatured is OK).  Put a stopper of some sort (a cork, for instance) in the hole and then hang the bolt about waist high at the edge of the orchard.  It will probably take several traps per edge, but edges along woodlines are most likely to catch beetles first.

Photo by Dr. Pete Schultz, VPI&SU

Photo by Dr. Pete Schultz, VPI&SU

Photo by Dr. Pete Schultz, VPI&SU.

Photo by Dr. Pete Schultz, VPI&SU.

Once attacks are detected on the trap, close-interval scouting can be initiated (check the trees every day or so for signs of beetles).  If you see toothpicks on the trees, apply a pyrethroid spray quickly to minimize damage and losses.  Unfortunately, barrier sprays applied as a preventative measure for other borers are not effective on these beetles.  They will provide protection for a few days or a week, depending on the weather, but ambrosia beetles do not eat the wood or bark so once the volatility of the insecticide has faded a bit they are not affected.

You can also reduce losses by removing the irrigation pipe collars that protect young trees from herbicides. Ambrosia beetles will attack inside the pipes where they can’t be seen.  That adds work, and means you have to delay herbicide application until they can be reinstalled once the trees leaf out completely. But collars have definitely contributed to extra losses for a number of growers. The spring green-up period is when the trees are most vulnerable, and once they have leafed out completely the risk of attack drops to almost zero unless there is some stress factor for the trees.

Ambrosia beetles are active all year long, and they are strongly attracted to stressed, diseased or injured trees.  Growers should be very alert to any problems with irrigation, especially during hot dry weather.  Keep tractors and other equipment well away from the trees to avoid injury that invites ambrosia beetles and other borers.

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Filed under Entomology, Pecans