November 13, 2010

1 - Don't eat bitter almonds that may have come from rootstocks.

Yard and Garden - November 13, 2010


My daughter bought a house with some over 50 year old almond trees. Both made a lot of fruit this year, but all of the almonds on one of the trees are very bitter. They did not notice it last year. They have only been in the house a couple of years so they really do not have much history with the trees. What might cause that to happen in two trees close to each other and receiving the same care?


Almond trees are not common in New Mexico. Heavy almond crops are even less common. This is something to be thankful for, however, the term "bitter almond" suggests reason for caution. Bitter almonds are often associated with high levels of cyanogenic compounds in the seeds (nuts). These chemicals, in the presence of stomach acid, release cyanide and are toxic. They should not be eaten. If you have eaten a few, that will probably not be fatal, but it is best to avoid eating bitter almonds. The sweet almonds are safe to eat

Reasons for one tree to produce sweet almonds and a nearby tree given the same care to produce bitter almonds may be due to the fact that the bitter almond tree may have died back sometime in the past. The tree existing now may have developed from a seedling (bitter almond) root stock. This may have happened when the trees were young if both trees are now about the same size. Since almonds have a tendency to flower too early, and be damaged by frost, they rarely produce almonds and the problem may not be apparent. In those years it is a pretty flowering tree, producing attractive flowers early in the spring and nice shade during the winter. This year, when they produced a heavy crop, the bitter almond was made more apparent. It is still a pretty flowering tree and casts a nice shade, but the nuts should be avoided.

If you want to have sweet almonds on both trees, you may be able to "top-work" the trees (graft sweet almond branches into all the branches, to make this tree produce sweet almonds, but it is important that no bitter almond shoots remain.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email:, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at, or at the Desert Blooms Facebook page.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!