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Tuesday, September 25, 2012

Agave Dying Suspected Overwatering But...


Q. The Agave in my front yard (maintained by HOA) is dying.  I was informed by an Aborist that it was getting too much water.  I relayed this to the HOA maintenance and when they looked at it they said it needed more water and ran another dripper line, which drips about every day. Can this once beautiful plant be saved. Pictures are 6 weeks apart and show how it has deteriorated.

Agave appearing to wilt from a watering problem, or is it?
This could also be from the agave weevil.

A. This is either too much water or agave weevil damage. The weevil deposits eggs in the crotches of the leaves at the base and the eggs hatch. The larvae of the weevil then invade the roots where they feed causing the agave to collapse just like in your picture. However, overwatering can cause the roots too rot easily and cause exactly the same type of symptoms; collapse of the outer leaves and eventual death of the entire plant. Unfortunately you get the same result and is not much you can do at this stage.
            I would predict the plant will die and it will have to be removed. American agave is probably one of the worst ones for agave weevil infestation. Replanting with a different agave like
Agave weevil in the roots of an agave. It is a light colored
or white grub near the center of the picture.
            Weber’s or Parryii will be more resistant to the weevil but not overwatering. Both of these are smaller and more in scale with homes landscapes.
            There are two types of overwatering. One is watering too much and the other is watering too often. This is more of the watering too often kind of problem. Wish I had a better story to tell.
            I have attached a brochure from the U of Arizona on this weevil problem and some recommended preventions from one of the arboreta down there. I also attached a picture of the weevil larvae you would find in the roots if that was the cause. They would be there now.

2 comments:

  1. More a Question. The outer edges of my Variegated Century Plant Marginata are turning pinkish-red and are curling inward a bit. Do you know why, please? Am I overwatering, or....?

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    Replies
    1. Could be lots of different reasons. The pinkish color comes about when the variegated parts (no green so no chlorophyll) starts to die or weakened health wise. It can be from a lack of phosphorus due to cold wet soils. If this color disappears when things start to warm up then it is a phosphorus deficiency because of cold soils. This plant is native to the sonoran desert mostly. It can be found growing natively in Arizona, Mexico,New Mexico and Texas. It does like warmer locations than what it finds in most of southern Nevada. Very well could be cold soils. But the color is there because the chlorophyll is not. The dark green/gray color of chlorophyll can cover it up. Make sure you water no more frequently than about every three or four weeks in the summer. Winter time maybe every two or three months. Water deep (18 inches deep) when you water and not shallow. Then hold off. if you water too often you will kill it.

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