Needle miners? - Ask Extension
I have several pine trees that seem to have needle miner damage. The needles look like the Ponderosa Pine Needle Miner photos in the book "Insects and...
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Needle miners? #171336
Asked March 24, 2014, 3:04 PM EDT
I have several pine trees that seem to have needle miner damage. The needles look like the Ponderosa Pine Needle Miner photos in the book "Insects and Diseases of Woody Plants" which I think is a CSU book.
The needles on the outer portions of the branches die back. Any new growth soon exhibits drops of sap and dies.
The book says that the miners have a lot of natural pests, so I just watched and thought they problem would go away. It is getting worse. Now that spring is here I would like to try appropriate treatment. Some photos from last fall are attached. Thanks.
The needles on the outer portions of the branches die back. Any new growth soon exhibits drops of sap and dies.
The book says that the miners have a lot of natural pests, so I just watched and thought they problem would go away. It is getting worse. Now that spring is here I would like to try appropriate treatment. Some photos from last fall are attached. Thanks.
Arapahoe County Colorado
Expert Response
The needle damage in your photos is unlikely to have resulted from needle miners.
The "part green, part brown" needles are much more likely to be the result of desiccation / drought. This occurs when loss of water through needles exceeds the rate of water uptake by roots, often after dry windy warm periods in winter.
This needle desiccation can happen as the result of deicing salt application nearby - on pavement, sidewalks, etc. Salts in excess damage or kill small roots that are active in water uptake - less water sent to needles means they "scorch" or partially brown. An excessive amount of fertilizer applied to the rooting area can cause similar browning...fertilizers are salts. Fertilizer applied later season can delay hardening of newest growth, keeping it succulent into fall, when it is more easily damaged or killed by cold snaps.
Small/limited rooting areas could result in browned needles like those in your photos.
Any kind of construction in the rooting area (like trenching) can sever or damage roots, resulting in less water uptake. Severe soil compaction in the rooting area can affect root health, resulting in less water uptake.
Affected needles will not re-green but will eventually drop. New growth from buds this May might "hide" some of the brown needles.
The "part green, part brown" needles are much more likely to be the result of desiccation / drought. This occurs when loss of water through needles exceeds the rate of water uptake by roots, often after dry windy warm periods in winter.
This needle desiccation can happen as the result of deicing salt application nearby - on pavement, sidewalks, etc. Salts in excess damage or kill small roots that are active in water uptake - less water sent to needles means they "scorch" or partially brown. An excessive amount of fertilizer applied to the rooting area can cause similar browning...fertilizers are salts. Fertilizer applied later season can delay hardening of newest growth, keeping it succulent into fall, when it is more easily damaged or killed by cold snaps.
Small/limited rooting areas could result in browned needles like those in your photos.
Any kind of construction in the rooting area (like trenching) can sever or damage roots, resulting in less water uptake. Severe soil compaction in the rooting area can affect root health, resulting in less water uptake.
Affected needles will not re-green but will eventually drop. New growth from buds this May might "hide" some of the brown needles.
I have added a couple more photos, taken last summer with a better camera, just to make sure that they don't change your diagnosis. They show how the problem first shows itself. If there is a new candle of growth on the branches with the browning needles they turn gray and quit growing. Often there is sap coming out of the dying tips.
The trees affected are near my house in rural Arapahoe county. There hasn't been any construction or trenching near them. There is no foot traffic near them and nothing extraordinary is going on that should compact the soil. I did fertilize them last year, but applied the same amount to other pines that weren't affected.
What should I do to try to try to revive them? Water more, do anything to the soil? The trees are 3 or 4 years old and I thought they were well established until the last summer. I give them a through watering about every 4 to 6 weeks. Thanks.
The trees affected are near my house in rural Arapahoe county. There hasn't been any construction or trenching near them. There is no foot traffic near them and nothing extraordinary is going on that should compact the soil. I did fertilize them last year, but applied the same amount to other pines that weren't affected.
What should I do to try to try to revive them? Water more, do anything to the soil? The trees are 3 or 4 years old and I thought they were well established until the last summer. I give them a through watering about every 4 to 6 weeks. Thanks.
Additional photos do not add any evidence for needle miner injury.
You might mulch the rooting areas with 2-3 inches of wood chips or pine needles. This will keep soils cooler, moist longer and keep soil surfaces from crusting. The down sides are that some mulches may blow easily in windswept areas and that rodents may find mulches attractive for nesting.
Suggest you cross-section a dead shoot where drops of sap have oozed; if hollow that may provide a clue.
It might be helpful to test your soil for salinity (salts) - pines, especially ponderosa pine, are pretty sensitive to root damage by high salts; that root damage is manifested as browning needles.
You might mulch the rooting areas with 2-3 inches of wood chips or pine needles. This will keep soils cooler, moist longer and keep soil surfaces from crusting. The down sides are that some mulches may blow easily in windswept areas and that rodents may find mulches attractive for nesting.
Suggest you cross-section a dead shoot where drops of sap have oozed; if hollow that may provide a clue.
It might be helpful to test your soil for salinity (salts) - pines, especially ponderosa pine, are pretty sensitive to root damage by high salts; that root damage is manifested as browning needles.
