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Pine Needle Cast: Disease or Pest?

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Friday, October 25, 2019 - 7:00am

Announcer: Farm and Family is a production of the Mississippi State University Extension Service.

Amy Myers: Today, we're talking about pine needle cast, disease or pest? Hello, I'm Amy Myers and welcome to Farm and Family. Today, we're speaking with Dr. John Kushla, Mississippi State University Extension Forestry Specialist. John, is pine needle cast caused by a disease or an insect?

John Kushla: Amy, this is a trick question. The answer is both. There are a couple foliar pests of pine manifesting themselves in the spring or summer. One is a defoliating insect. The other is a foliar fungus. Both will brown the foliage or pine needles.

Amy Myers: So, let's start with the bug.

John Kushla: Colaspis pine eyes is a defoliating beetle. This insect attacks many Southern conifers. The adult beetles are generally tan in color, oval in shape, and about three-sixteenths of an inch long. The adults lay eggs on the understory brush and the larvae eat grass roots during the summer and then the insect overwinters in the soil.

Amy Myers: And what damage does the beetle do to conifers?

John Kushla: The adult beetles hatch in the spring and eat the older pine needles. Most conifers are evergreen and carry needles two or three years. The exception is bald cypress, which is deciduous and so the beetle attacks new foliage on this tree. The adult eats edges of the needle, leaving a serrated appearance and eventually, the needles die, giving a scorched appearance to the tree canopy.

Amy Myers: So, which conifer species are susceptible to pine needle cast?

John Kushla: The beetle tends to prefer slash pine in Southern Mississippi but will attack any of the Southern pines, including loblolly, long leaf pond pine, short leaf spruce pine and Virginia pine. It will also attack bald cypress and spruce. Infestations tend to be worse on trees bordering grassland or surrounded by grass, such as in yards or pastor.

Amy Myers: So, is this a serious pest?

John Kushla: Not generally, for a couple reasons. The beetle life cycle has only one generation per year. On evergreen conifers, the beetle eats the older needles. So, new needles still flush out. Conifers rarely die from this beetle attack, so control in forests is not necessary.

Amy Myers: Are there insecticides that are available to control this beetle?

John Kushla: Yes, for controlling the Colaspis beetle on ornamental trees, such as on golf courses or in your yard. These include formulations of malathion, carbaryl, Orthene or Sevin. Some of the organophosphates are restricted-use pesticides and require a pesticide applicators license to purchase. Always follow label directions when using pesticides.

Amy Myers: And what is the actual disease causing pine needle cast?

John Kushla: Pine needle rust is caused by a fungus Coleosporium species. It can infect any of the Southern pines. As a rust, this fungus needs an alternative host to complete it's life cycle. Spores from the trees infect forbes in the composite family like asters and goldenrods. Spores from the forbes infect pines. The rust generally infects pine needles in the late summer or early fall. The trees will develop dead spots on the needles, which may turn yellow or even die completely.

Amy Myers: And what is the severity of this disease?

John Kushla: Young pines are most vulnerable since the entire crown may become infected. Fungal populations can be especially high during years with wet autumns. Infection in older trees is generally limited to the lower limbs and so it's not so serious.

Amy Myers: Are there any controls that are available?

John Kushla: Unfortunately, no fungicides are labeled to treat this infection on pines. However, the best control is by removing the alternative hosts with site preparation. Since young pines are most vulnerable to severe injury, this is the best protection.

Amy Myers: So, give me a summary of what we've talked about today.

John Kushla: Pine needle cast can be caused by an insect or a disease. Neither is a serious situation to older pines. If you have further questions, contact your local extension office or call me at 662-566-8013.

Amy Myers: Today, we've been speaking with John Kushla, Forestry Specialist. I'm Amy Myers then this has been Farm and Family. Have a great day.

Announcer: Farm and Family is a production of the Mississippi State University Extension Service.

Department: Forestry

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