Cold Hardy Avocado

Cold Hardy Avocado

Avocados can easily be grown in the home, garden, orchard or patio. They can be grown in America with great success and thrive in warm climates. They require little to no pruning and are easily contained.

Seasonal information: 
Cold hardy avocado trees typically do well areas that have mild winters. The cold hardy avocado is specially adapted to our cooler climates. They will grow in shade but prefer full sun when possible. A cold hardy avocado fruit has a 25% yield rate, which means, only 25% of the flowers will make fruit.  The skin of the fruit is paper-thin, and purple-black in color. They have high quality flesh with a large amount of oil content and are hardy to about 20F once established.

The roots are highly competitive, so be sure to allow space or consider potting your cold hardy avocado tree. Give the tree plenty of room, up to 20 feet if not containerized, to avoid competition. The Avocado can provide a perfect windbreak for windy inland canyons or beaches.

Planting instructions: 
Planting in fall or at the start of the rainy season is best. In cold winter areas, plant in the early spring so the tree has a chance to extend roots before winter sets in. Water the tree well before planting and choose a sunny area. Then, dig a hole larger than the pot you purchased it in and one to two inches deeper. Remove the tree from the pot and separate the roots, careful to avoid breakage. Water the tree and fill in the dirt as you water. Cover the new soil with mulch to retain moisture and keep weeds away.

Cold hardy avocado trees may not need to be watered during the winter season or rainy months, but watch for extended mid-winter dry spells. Over-watering can cause root rot, which is the most common cause of avocado death. To test to see if your tree has sufficient moisture and drainage, dig a small hole at least nine inches deep. Pick up a small handful of dirt and squeeze it. If it is moist (retains its squeezed shape), do not water. If it is dry and crumbly in your hand, you should water. Watch soil moisture carefully at the end of the irrigating season. Make sure the soil has dried out before winter arrives.

While the roots prefer to stay on the dry side, Avocado leaves love humidity.  Indoor Avocados will do best if misted daily especially when you are running your heat during cooler months.  You can also use a humidifier or fill your pot’s saucer with rocks and add water; place your plant on the rocks ensuring the bottom of the pot is above the water line.

Commence feeding young trees after one year of growth by using a balanced fertilizer four times yearly. Older trees benefit from feeding with nitrogenous fertilizer applied in late winter and early summer. Yellowed leaves indicate iron deficiency. This can usually be corrected by spraying trace elements containing iron. Mature trees may also show a zinc deficiency.

If you are in a colder zone, and plant your Avocado in a container… or in a warmer zone planting it in the ground, make sure to cover (with burlap) during the first few years to prevent any browning over the winter.

Weed Control: 
Mulching will help prevent other weeds from growing nearby, though the cold hardy avocado tree rarely has this problem.

SUDDEN LEAF DROPPING:  Unusual temperature changes cause plants to drop leaves. Late or early frosts typically cause this, as does something as subtle as moving potted fruit trees inside or out. Sometimes plants drop leaves to rid themselves of leaf parasites. Leaf drop is natural and the plant will typically replace its foliage during its natural growing season.

Deer and Small Animals:
Deer can be a particular nuisance to your avocado tree, particularly when it has new growth as they like to nibble on the tree’s tender shoots. If this happens it can stunt the growth of the tree and also make it vulnerable to sunburn; before long your tree is ruined.
If you do have wild deer in your area you can protect your tree by wrapping the bark with trunk wraps. This may also help keep smaller critters like opossums, rabbits and squirrels from attacking your tree. Another alternative for keeping deer away is to put deer-deterring plants around your trees. Some of the most effective include Black-eyed Susan, Butterfly weed, Foxglove beardtongue, Nodding Onion, Stiff goldenrod, and Lance-leaved Coreopsis.

Ambrosia Beetles
These insects burrow into tree trunks, branches and stems. The beetles also introduce fungi into the tree where it develops mycelia in the tree’s tissues. This in turn constricts the tree’s branches. They can be treated with permethrin.

Avocado Bud Mite
This tiny insect can be found feeding on buds and developing fruit. They cause small spots of decay, fruit discoloration and malformation. The adult has a yellowish body. Infestations begin from March through May. They can be treated with an insecticidal spray.

Avocado Lace Bug
Increasingly severe outbreaks of this bug have been seen since the 1990s. The insects are small, oblong and brown with ‘lacey’ wings. They are found on the underside of the leaves where they suck out the plant’s juice. They live in colonies that crowd the leaves’ undersides. They begin to build up from January through March.

Avocado Tree Girdler 
This adult snout beetle attacks younger trees up to six inches in diameter at ground level. The insect larvae created burrows as they feed. You should examine your trees twice a year, and look for the reddish frass extruded by the larvae. Treat the tree by removing the larvae and painting with tree wound paint.

Brown Garden Snail
The Brown Snail has a soft, slimy body and a hard shell with yellow bands. They feed on the leaves and shoots of the avocado and stunt the growth of trees that have had topwork.
Snails are more active during the night time, so you should check your trees in the early morning. Both snails and slugs are repelled by copper. Fitting a band of copper around your tree’s truck will stop them gaining access from the ground but you also need to ensure the canopies are clear.

Leaf-rolling and web spinning caterpillars can infest avocado trees, feeding on the blooms and leaves. There is also a looperEpimeces detexta (the lava of a grey-white moth) that feeds on avocado leaves in Florida. Looper will also feed on the tender new shoots on the upper part of the tree and even the fruit. Looper infestations tend to be more prevalent during the spring and summer months. They can be treated with an insecticidal spray or dust.

These are small sucking insects that feed from and interest their eggs into young avocado buds as they are opening. Attacks will destroy flowers and cause recently set fruit to fall. Check fruit for a wound which may lead to decay. Trees are usually vulnerable to Mirids during flowering and early fruit setting stages. They may be prevented by regularly cutting grass and weeds surrounding the trees. Mirids can be treated with Malathion.

Scale Insects 
Scale insects such as black and red scale can sometimes be a problem for avocado trees. They usually infest between May and July and can be treated with insecticide.

Spider Mite
Florida avocado trees are particularly prone to the red mite. It begins its feast on the upper surface of the leaves then the midrib and finally around the leaf veins. These areas will turn brown. You may also see evidence of the mite’s casts. If you can see 6 or more mites per leaf you will need to spray with insecticide.

The EPA has listed a number of insecticides that have been cleared for use on Avocados. These are: 
• Bacillus thuringiensis (Biobit, Cutlass, Dipel, Javelin, Vault, XenTari)
carbaryl (Sevin)
malathion (Cythion)
metaldehyde (slugs and snails)
methomyl (Lannate)
permethrin (Ambush, Pounce)
pyrethrins + rotenone (Pyrellin)
oils (Sun Spray, Volck oil)
rotenone (Rotacide)
soap, insecticidal (M-Pede)
sulfur (Thiolux, SuperSul)
diatomaceous earth + pyrethrin + pbo (Diatect Organic Plus)

This is a fungal disease that can cause problems for mature avocado fruit, though it will sometimes also infect younger fruit, twigs and leaves. It causes black or brownish circular depressions on the fruit. These rapidly spread and cause the fruit to rot. The fungus can be treated with applications of a fungicide that has been approved for anthracnose.

Powdery Mildew
It is not uncommon for avocado trees to become infected by powdery mildew. If this is left untreated it can affect the tree quite severely. The infection begins with dark green-purple spots on the undersides of the leaves, followed by with powder growth on the upper and lower surface. Fungicides approved for powdery mildew will fix it.

Pseudocercospora Spot
This common avocado tree disease occurs in humid weather. It produces small brown lesions on fruits, stems and leaves. Some of the lesions may also grow a furry mass. This disease should be treated with treated with azoxystrobin or copper spray for avocado trees.

Root Rot
Root rot caused by the Phytophthora fungi is not treatable. It causes the infected tree to die. The feeder roots blacken and the leave gradually wilt and fall. To protect your tree from this type of infection you should plant it in well-drained soil and avoid over-watering.

Scab is caused by the fungus, Sphaceloma perseae. It occurs on twigs and leaves growing on the upper half of the avocado tree as well as the fruit. The infected fruit develops oval brown, slightly raised spots, which gradually sink. This disease should be treated with treated with azoxystrobin or copper spray for avocado trees.

Fungicide Caution 
Always use a fungicide, azoxystrobin or copper spray that has been approved by the EPA to treat specific disease on avocado trees. Always follow the directions exactly. Remove dead or infected material from the tree. Do not compost it.

Pruning: Cold hardy avocado need little to no training. These days, staking is avoided as it can cause strain on the tree. Fencing the tree with plastic mesh for the first two or three years will produce the desired result. You may wish to trim the tree’s skirts to deter small critters, but other than that, this tree is never pruned.

Pollination: You can increase your hardy avocado’s chances of pollination by planting two or three trees in the same area.