April’s Ag Advice

April's Ag Advice
We need your help! SDSU Extension State Climatologist Dennis Todey is looking for local volunteers who would be willing to collect and report local precipitation totals. The goal of this program is to try to get a better handle on how much rainfall actually falls across the state. We know that in the state of South Dakota, especially during dry times, the amount of precipitation variability is quite great.

South Dakota State University and the three National Weather Service offices in South Dakota are working together on this project. Our project is part of the CoCoRaHS network. CoCoRaHS, stands for "Community Collaborative Rain, Hail and Snow Network". According to Todey, the project started in Colorado about 10 years ago after a big flood event there. After that event they decided that they needed to determine in much higher detail how much precipitation fell over these areas including small areas like towns. We are also trying to better define this situation by getting more places where we record precipitation across the state.

Todey said the system relies on trained volunteers who will report precipitation daily via the CoCoRaHS Web site. "Our kickoff date is June 1. That's the date we'll be able to get people signed up and the date that we will start reporting precipitation for the network across the state," Todey said.

CoCoRaHS is an unofficial network. The official data will still be the National Weather Service cooperative observers across the state. "This network does not replace those observers by any stretch, but it adds on to them to try to get better detail of what is happening across the state," Todey said.

SDSU and the National Weather Service will be carrying out some training prior to June 1 to help volunteers gear up for being part of the CoCoRaHS network. The National Weather Service offices and the state climate offices are the state and regional coordinators. They will also be identifying county coordinators to help recruit volunteers and take observations from people who don't have Internet access, Todey said.

South Dakota will be the 19th state to join the network. Find more details about the network online at its Web site, http://www.cocorahs.org/. If you are interested in being a volunteer please contact SDSU Extension State Climatologist Dennis Todey for more information at (605) 688-5678.

I hope that through monitoring precipitation we will also be able to look at disease frequency. I have had my first case of ash rust and in my opinion this is a little early in the season to be seeing this disease. But I think that we have to come to some agreement that this is not a typical year and anything can happen.

Ash rust can infect several species of ash including green, white, and black. The disease, caused by the fungus Puccinia sparganioides, spends part of its life cycle on ash and the rest on cordgrass in marshes.

In the spring during warm wet weather, spores are released from infected grasses and windblown to nearby ash trees. Infection results in conspicuous swellings on leaves, twigs and petioles. Infected leaves may be distorted, necrotic (brown or dead), and/or wilted with heavily infected leaves dropping from the tree. Swellings on the infected petioles and upper leaf surfaces of ash trees develop yellow to orange spots in late June. These spots contain masses of orange powdery spores which are windblown from ash trees to cord grasses. The fungus then infects the grasses to complete its life cycle and overwinter.

Usually, ash trees are not seriously damaged by this disease. Therefore no preventive fungicides are recommended. However, successive infections can weaken plants making them susceptible to stressful environmental factors. Cultural practices such as watering during dry periods, mulching, and fertilizing may increase vigor of stressed trees. Pruning infections will remove spores that can reinfect cordgrass. This may lessen the number of infections the following year. Removal of all nearby cordgrass will disrupt the life cycle of the fungus, thereby preventing new infections. However, removal of grasses is not always feasible.

Another threat that we will see soon that could affect our ash trees are the ash borers. I am talking about the lilac/ash borer (a native ash borer) that is a problem for our stressed ash trees. The adults will be out in the next couple of weeks so we need to be prepared to spray for the adults. I am not talking about the Emerald Ash borer as this insect has NOT been identified in South Dakota.

The first thing to remember regarding borer control is that borers tend to attack trees under stress. The best borer control is a healthy, vigorous tree. This means watering during dry periods and mulching under the tree to reduce competition from other plants and provide a more root-friendly environment. But sometimes insecticides are needed to help protect trees that have already been attacked. Unfortunately, borer control has become more difficult since Dursban was taken off the market.

There are several products available for controlling the borers. These products are listed below:

  • Bayer Tree and Shrub Insect Control (imidacloprid): This product is labeled for both roundheaded and flatheaded borers. It contains the same active ingredient found in Merit and is systemic in the tree. Historically systemic insecticides have given poor control of borers. It appears that imidacloprid is better on flatheaded borers than roundheaded borers though even the results on flatheaded borers are inconsistent. Flatheaded borers are more likely to be controlled because they feed more in the vascular tissue than the roundheaded borers and are more likely to take up the insecticide. Examples of flatheaded borers include the flatheaded apple tree borer and the bronze birch borer. The lilac/ash borer is a roundheaded borer.
  • Fertilome Borer, Bagworm, Leafminer and Tent Caterpillar Spray (spinosad): The active ingredient of this product is derived from actinomycetes (bacteria) in the soil. There are not many studies out on this chemical to show the level of effectiveness so use with caution.
  • Permethrin: Permethrin is found in numerous products including Bonide Eight, Spectracide Bug Stop Multipurpose Insect Control, Fertilome Indoor/Outdoor Insect Spray and Fertilome Kill-A-Bug II. However, these products only have Peach Twig Borer and Lesser Peachtree Borer on the label. Fortunately, permethrin is also found in Hi-Yield Lawn, Garden, Pet and Livestock Insect Control and the commercial product Astro. Both of these products have a wide borer label including both roundheaded and flatheaded borers.

    Note that the Hi-Yield product has a virtually identical insecticide called Garden, Pet and Livestock Insect Control that does not have a wide borer label. The easy way to tell the two apart is packaging. The latter product comes in an 8-ounce bottle and the other (the one you want) in a 32-ounce container.

    Permethrin is not systemic and works by killing the young borer larva as it hatches from the egg and tries to bore into the bark.

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