Trouble-shooting a holly

Arrows point to the damage that indicates a holly leaf miner is mining within each of those leaves. Catching the problem in its first year is key: Remove the leaf while the miner is still within and burn that foliage: Voila, no next generation of miners. 
 

The major issues, with links to great answers

  • Scale insects,
  • leaf spot,
  • holly leaf miner and
  • winter damage (dessication)

are the problems holly growers might have to deal with.

Standard procedures applies: Keep the plant healthy and it will resist problems on its own, but "shake hands" with the plant regularly. Saying hello every few weeks focuses your attention so you can see signs of any trouble in early stages when they are most simply managed.

 

Scale:  http://edis.ifas.ufl.edu/in649

Cottony camellia scale on holly: http://oregonstate.edu/dept/nurspest/cottony%20camellia%20scale.htm

Below: Cottony camellia scale on a holly.

IlexScale5808s.jpg

Don't wait until the scale population is so heavy as what you see here (above). Watch for early signs, such as the sooty mold that grows where the sticky liquid excrement from scale insects coats leaf surfaces and twigs. Sooty mold is what has made those interior leaves so dark.

 

Leaf miner: http://www.hgic.umd.edu/_media/documents/publications/holly_leaf_miners.pdf

 

Leaf spot: http://www.ppdl.org/dd/id/holly_leafspot-holly.html

Also: http://extension.umass.edu/landscape/fact-sheets/holly-leaf-spot

Note: "Spine spot" can be mistaken for a fungal leaf spot. If you see small gray spots with purple halos, put spine spot on your suspect list. It's caused by the piercing of a leaf by adjacent leaves.

Below: This is not a variegated holly but one that suffered drying wind. The tiny wounds are spine spot, caused by that same wind which rattle nearby leaves so their tips pierced this blade. This damage cannot be reversed. Leaves do not heal,  but hang in until they are too damaged to support themselves. This leaf still has 75% of its surface, so it's only lost 25% of its energy production capacity. Protect the plant from future wind, prune to encourage new growth at all depths, and clean new foliage will replace this.

IlexSaltDmgN2567as.jpg

 

Winter damage. Dessication from wind in any season. Photo above, and see the problem-round-up below.

 

For an overall holly problem round-up: http://www.clemson.edu/extension/hgic/pests/plant_pests/shrubs/hgic2055.html

Also: http://www.ces.ncsu.edu/depts/ent/notes/O&T/specificplants/note143/note143.html

 

And one "How 'bout that, now!" item, look what you find here if you read all the way into the "Damaging Agents" section: Midges making the berry stay green from http://www.na.fs.fed.us/pubs/silvics_manual/volume_2/ilex/opaca.htm

 

 

Related links