April 27, 2013

1 - Some plants produce extrafloral nectaries that look to some gardeners to be insects on the leaves, don’t worry about them.

2 - Frost, wind, and cold weather that reduced bee activity may result in few to no fruit in early blooming varieties this year.

Yard and Garden April 27, 2013

Q. #1

I bought a Stella Cherry tree over the weekend and after a 7 to 10 mile ride in the back of a pick-up it was placed in our new greenhouse. Today I found numerous spots on the leaves from the bottom to the top of the tree. Some of them look sappy and clear and some are red...some are green. I tried to take a small green one off and it was attached so tight I had to use my finger nail to release it. I have never had a cherry tree before and do not know if these are normal or some sort of problem. Any help you can give me will be appreciated. I tried to take very close up pictures so sorry they are not super clear...I will use my tri-pod if you need clearer pictures.

K. Real

Silver City

A. #2

The pictures you sent do not indicate a problem. Your pictures clearly showed extrafloral nectaries which made the identification easy. These are natural structures produced on the petiole or lower portion of the edge of leaf blades. They may look somewhat like insects on a petiole, but they are part of the plant and serve an important function. Species of Prunus (cherries, plums, apricots, peaches, nectarines) produce what are called extrafloral nectaries (nectar producing structures outside the flowers). Plants in other some other genera may also produce these interesting structures. These are glands that secrete a high sugar liquid (nectar) to attract protective insects (especially ants). The ants and other insects attracted by the nectar receive food from the nectaries and, in return, provide protection against other insects and animals that would damage the plant. Ants often protect aphids on plants (this is bad), but in the case of plants with extrafloral nectaries, the ants do not need the aphids and may actually protect the plant (in your case cherry tree) from aphids. If aphids do develop in high numbers, just wash them off with a strong stream of water.

Q. #2

My plum tree blossomed profusely this spring, but now I cannot find any fruit on the tree. Will they develop later?



A. #2

If it has been at least 2 weeks since the trees blossomed, you should be able to see small fruit forming. The absence of fruit may be due to the late freezes we had this spring. After and during flowering, the flowers and small fruit are easily damaged by temperatures below about 28 degrees. This is not uncommon in New Mexico. Another factor to consider is that when the weather is cold and windy, bees may not be active. Without bees actively pollinating the flowers, fruit will not form. Drying winds can also damage developing fruit, causing them to fall from the tree. All of these factors have been present in New Mexico this year. In some areas, the trees may still produce fruit. Some trees may produce fewer fruit than usual and some may produce no fruit this year. This may allow the tree to strengthen itself by directing food produced by photosynthesis into development of the tree, so that next year it can produce a bumper crop if the weather permits.

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: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.


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

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