Fruitless mulberry tree leaf

Morus alba Fruitless Cultivars: White Mulberry1

Edward F. Gilman and Dennis G. Watson2

Introduction

This group of mulberries is fruitless, a definite plus when compared to the mess created by the abundant fruits of the common white mulberry. The plant quickly forms a dark green mass of foliage from a short trunk, or group of trunks. This gives many people reason to plant the tree. However, it is quite sensitive to ice damage, has invasive surface roots and drops leaves in summer.

Figure 1.

Middle-aged Morus alba fruitless cultivars: White Mulberry

General Information

Scientific name: Morus alba Pronunciation: MOE-russ AL-buh Common name(s): White mulberry Family: Moraceae USDA hardiness zones: 3B through 9B (Fig. 2) Origin: not native to North America Invasive potential: little invasive potential Uses: shade; specimen; bonsai Availability: somewhat available, may have to go out of the region to find the tree Figure 2.

Range

Description

Height: 20 to 30 feet Spread: 30 to 45 feet Crown uniformity: irregular Crown shape: round, spreading Crown density: dense Growth rate: fast Texture: coarse

Foliage

Leaf arrangement: alternate (Fig. 3) Leaf type: simple Leaf margin: lobed, serrate, dentate Leaf shape: ovate Leaf venation: pinnate Leaf type and persistence: deciduous Leaf blade length: 2 to 4 inches, 4 to 8 inches Leaf color: green Fall color: yellow Fall characteristic: showy Figure 3.

Foliage

Flower

Flower color: green Flower characteristics: not showy

Fruit

Fruit shape: no fruit Fruit length: no fruit Fruit covering: no fruit Fruit color: no fruit Fruit characteristics: no fruit

Trunk and Branches

Trunk/bark/branches: branches droop; showy; typically one trunk; thorns Pruning requirement: needed for strong structure Breakage: susceptible to breakage Current year twig color: green, gray Current year twig thickness: thin Wood specific gravity: unknown

Culture

Light requirement: full sun, partial sun, or partial shade Soil tolerances: clay; sand; loam; acidic; alkaline; extended flooding; well-drained Drought tolerance: high Aerosol salt tolerance: unknown

Other

Roots: not a problem Winter interest: no Outstanding tree: no Ozone sensitivity: sensitive Verticillium wilt susceptibility: resistant Pest resistance: resistant to pests/diseases

Use and Management

Fruitless white mulberry should be grown in full sun or partial shade on any well-drained soil. Although it is tolerant of air pollution and dry conditions, the tree will perform its best on moist soils. Leaves often drop in dry weather.

The species is invasive and gruits cause a mess on walks and driveways. For this reason, only fruitless cultivars are recommended.

Propagation is by cuttings or grafts.

Fruitless cultivars include ‘Bellaire’, ‘Chaparral’, ‘Hempton’, ‘Stribling’, and ‘Urban’.

Pests

Pests are scale and mites.

Diseases

Leaf spot, bacterial blight, powdery mildew, and cankers may infect this tree.

Footnotes

This document is ENH-567, one of a series of the Environmental Horticulture Department, UF/IFAS Extension. Original publication date November 1993. Revised December 2006. Reviewed February 2014. Visit the EDIS website at http://edis.ifas.ufl.edu.

Edward F. Gilman, professor, Environmental Horticulture Department; Dennis G. Watson, former associate professor, Agricultural Engineering Department, UF/IFAS Extension, Gainesville, FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county’s UF/IFAS Extension office.
U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.

Mulberry leaf spot, in which the leaves turn yellow with dark spots, is caused by the fungus Cercospora moricola. Fruitless mulberry trees are especially susceptible to this disease. Trees may be sprayed with fungicide, though trees will generally survive without treatment. To prevent reinfection, gather and remove all fallen leaves. Popcorn disease, which results from an infection of the fungus Ciboria carunculoides, gets its name from the popcorn-like appearance of infected mulberries. While popcorn disease will decimate the harvest of mulberry trees grown for their fruit, it’s harmless on ornamental trees. To treat trees infected with this disease, pick and discard all infected berries, including all fallen fruit. Leaves that appear to be covered with a coating of rust are symptomatic of the aptly named leaf rust disease, caused by the fungi Aecidium mori and Cerotelium fici. This disease causes trees to shed leaves early, but will not otherwise harm the tree. If desired, spray the tree with fungicide, though the disease might also clear up on its own.

Issue: May 3, 1999

Tree didn’t leaf-out

Question:

I have a fruitless mulberry tree that is approximately 15 years old and has always done well even though the trunk has a bad split in it that has been there since 1991(never knew what caused the split). Anyway, this year the tree budded out but then most of the buds died off, and it has very few leaves on the tree (maybe two or three dozen on the entire tree). I don’t know what has happened to it unless when I sprayed for weeds it damaged the tree. If at all possible, I would like to be able to revive it if it is not too late. I have always used a broad leaf weed killer on my yard and it has never caused any damage to the tree before, so I’m not sure what has happened to the tree. Could you please offer any suggestions on how to revive it?

Answer:

You have described a tree with many problems. First, to address a safety issue if the tree is near your home or the street. Because of the split, it has the potential to fall causing damage or injury. So, first, do you really want to save the tree? It might be wise to have a local tree care professional who has experience in dealing with hazardous trees inspect the tree and make recommendations.

The reason that it has few leaves could be due to many factors. Here in New Mexico this year, my first thought would be of the late freezes which have been common across the state. Freezing weather after the tree has developed leaves, or as the buds are beginning to open, can kill the new buds. The tree has small buds at the base of the other buds as insurance against this occurrence, but it may take some time for these buds to begin to grow. If you see growth developing from these buds, the tree has dealt with the problem itself. However, if freeze injury is the cause, you may find that some of the twigs and branches were injured beyond their ability to recover. Any dead or severely damaged branches should be pruned. Contact your local Cooperative Extension Service Office for information on proper pruning techniques. The symptoms of freeze injury may continue to manifest themselves over a period of several years, so don’t be surprised to see continued dieback and weak growth for the next couple of years.

Disease may be the problem. The fact that the trunk is split suggests that fungus problems could be present. This would be best diagnosed by someone onsite. Contact your local Cooperative Extension Service Office or Master Gardeners for help with that.

The herbicides may also be the problem. Even though you have used herbicides for several years, you may have a cumulative effect and interaction with the other problems mentioned above. Have you been seeing misshapen leaves on the tree? Broadleaf herbicides at low levels will often cause the leaves to be distorted, but over time the effect may be to kill or severely injure the tree. Did you change the herbicide you used last year? A new or different herbicide would have different effects. Again, consulting the experts at your local Cooperative Extension Service Office would be helpful in identifying the problem.

Fruitless Mulberry Tree Diseases

Green leaves image by Mykola Velychko from Fotolia.com

Fruitless mulberry trees are fast-growing and fairly large, providing dense shade and thick, lateral branches for climbing. But they are fairly disease-prone and also tend to have shallow roots, which can make them difficult to maintain. The best way to keep your fruitless mulberry happy and healthy in your yard is to know the signs and symptoms of diseases so you will be able to spot trouble and avert serious disaster before it strikes.

Mulberry Leaf Spot

Mulberry leaf spot is a fungal infection that attacks the leaves of the fruitless mulberry. The leaves first will develop black spots. Left unchecked, mulberry leaf spot will cause malformed leaves to grow, then yellow quickly and fall. Use sterile pruning to remove all affected leaves and small branches. Dispose of debris in a garbage bag or by burning so no infected leaves or branches are lying on the ground near the tree to cause a second infection. If your pruning does not get the disease under control, you can use a fungicide to eradicate the problem. In most cases, mulberry leaf spot will not kill your fruitless mulberry, but it can weaken it and allow secondary infections access to the plant. It’s also a cosmetic problem.

Armillaria Root Rot

Armillaria root rot is also called oak root fungus, but it also attacks mulberry varieties, including the fruitless mulberry. The first sign of this rot will be that the tree develops stunted, discolored leaves that quickly fall instead of a healthy canopy. You may also notice mushrooms sprouting at the base of the tree, and branches may start dying. Once a fruitless mulberry develops root rot, you must remove the tree completely before the fungus spreads to other plants. This infection cannot be cured. The best way to prevent armillaria root rot is to make sure that the soil is well-drained and that there are no roots from previous plants in the ground when you plant your fruitless mulberry.

Nectria Canker

Fruitless mulberries are prone to developing cankers if the tree has any type of surface wound. The cankers start out as sunken areas on the branches or trunk. At this point, they are fairly hard to distinguish from the healthy part of the tree. But after a time, the canker will start to swell and become dark and corky. This can cause the leaves on branches that are infected to turn brown or wilt. To resolve the issue, you must remove the canker. The best time to do this is when the weather is cool because the bacteria that cause the canker are less likely to reinfect when they are cold. If the canker has girdled or killed a branch, remove the entire branch 4 or 5 inches below the canker. Dispose of debris in garbage bags or by burning rather than leaving it on the ground.

Mulberry

Mulberry is the name given to several species of deciduous shrub or tree in the genus Morus (family Moraceae) which are grown for their edible fruits. The genus includes white mulberry (Morus alba) and red mulberry (Morus rubra). Mulberries are small to medium sized shrubs or trees with a thick tan-gray ridged trunk and light green leaves which vary in shape depending on variety. Leaves are arranged alternately and are lobed or unlobed, cordate (heart-shaped), dentate (toothed) and acuminate (tapering). The trees produce small green-yellow flowers in dense spikes and an oval aggregate fruit made up of individual drupelets. The fruit can be white, pink or purple to purple-black in color and contains numerous brown seeds. Mulberry can reach a height of 15 m (49 ft) and are quite short lived, with an economic lifespan of around 15 years. Mulberry is believed to originate from China.
White mulberry tree
Male inflorescence
Ripening fruit
Red mulberry leaves
Unripe fruits
Mulberries
Female inflorescence
Unripe fruits
Red mulberry ‹ ×

Uses

Mulberries can be eaten fresh or used as fillings for tarts and pies. The fruit may also be used to make jams and jellies. They have been traditionally planted as a food source for silk worms.

Propagation

Basic requirements Mulberry trees should be grown in sunny locations, preferably in a deep soil. Mulberries are reasonably tolerant of drought, particularly white mulberry and can be grown successfully in poor soil. Mulberry will grow well in a variety of soils but optimum growth will be achieved when planted in a deep well draining loam with a slightly acidic pH of between 5.5 and 6.5. Fruit yields are increased when trees are positioned in full sun. Mulberry trees are cold hardy, although the specific temperature at which they will be damaged varies by variety. Some white mulberries can withstand temperatures of -32°C (-25°F). Propagation Mulberry trees can be propagated from seeds, cuttings or by grafting. Seeds should be collected from ripe fruits and removed by macerating the fruit in a water bath. Seeds which sink to the bottom of the bath are viable and can be planted immediately or dried and cold stored for planting later. Trees grown from seed can take 10 years or more to produce fruit. Cuttings can be taken during regular pruning of the tree. Branches should be 22 to 30 cm (8.6–11.8 in) in length and possess a minimum of three buds. Cuttings should be planted immediately. Grafted plants produce stronger root systems than trees produced by any other method of propagation. Grafting is usually achieved by budding in the Spring. Planting In the case of mulberry bushes, seedling are transplanted when they have reached 10–15 cm (4–6 in) in height. Seedlings for mulberry trees should be allowed to grow larger, usually at least 1 m (3.3 ft) in height and are trained prior to planting. Mulberry trees do not need to cross pollinate but if growing more than one tree they should be spaced 1.6 m (5.2 ft) apart. General care and maintenance Although established trees are relatively tolerant of drought, mulberries should be provided with additional irrigation during dry periods. The trees require little fertilization and a single annual application of a balanced fertilizer is usually sufficient to meet the growing requirement of the trees. Once trained, little pruning of the trees is required. Dead and damaged wood should be removed at the end of the growing season. Harvesting Mulberry fruit is usually ready for harvest in late Spring. The fruits are usually harvested by hand either by picking them from the tree directly, or by shaking the branches.

Duke, J. A. (1983) Handbook of Energy Crops. unpublished. Available at: http://www.hort.purdue.edu/newcrop/duke_energy/morus_alba.html#Cultivation. . Free to access.

Mulberry tree – issues with leaves

wondering when I know it’s time to repot? It came in a plastic container (inside the decorative one) that drains very quickly, which I’ve heard isn’t good. OTOH, I’ve heard they don’t like too much room and to wait for roots to stick out the bottom before repotting. 9 of 10 people that give advise on the internet are guessing or repeating advise they read somewhere else – whether it’s appropriate or not. It’s time to repot at the point in time where (when?) you can lift the root and soil mass from the pot intact. Root congestion probably starts to be somewhat limiting a little before that point, but not seriously, so the "when you can lift the root/soil mass from the pot intact’ is simple to remember and simple to verify. I use that as my own reference point. No plant "prefers" to be grown tight. If it did, Mother nature would have arranged for roots to occupy a little pot-shaped root ball directly under the plant’s stem. There are sometimes good reasons to allow or use the stress associated with root congestion to achieve an effect or bend the plant to your will, but it’s inaccurate to simply announce any plant likes to be root bound. Repotting is different and more involved with potting op. The former includes bare-rooting the plant, pruning roots, and repotting it in a fresh batch of soil. Potting up is little more than putting the plant in a larger pot and filling in the void at the bottom and sides with fresh soil. The former ensures all limitations imposed by root congestion go away; the later ensures limitations imposed by root congestion remain until the time someone actually gets their hands in the root/soil mass to correct the root issues and congestion. This holds true even if the plant were to be planted out (in the landscape). When keeping the best interest of the plant in mind, that you discover it’s time to repot isn’t reason enough to repot the day after. Timing heavy work like hard pruning and repotting is best done in consideration of the plant’s natural rhythms. If you repot a healthy tropical ficus in fall or winter, it might take several months to recover to the point top growth can resume. Repot it in very late spring (early spring is not a good choice), as in just before the summer solstice (I use Father’s Day as a reference point) and the plant will be pushing new growth in 1-3 weeks. It’s better to allow the plant to suffer some small amount of stress from root congestion and repot when the plant is about to be at its most robust state in the growth cycle than to repot when the plant is just trying to make it until next spring when it’s at its best. I would only repot out of season if I knew or strongly suspected the plant would be down for the count before a more appropriate time to repot rolled around. I’ve been pruning back slowly so as not to shock, pruning in the early fall when I want to incentivize root growth over winter. Usually my ficus drops a lot of leaves over winter (we are in New England). I’m hesitant to do a major trim in the spring because that is when I want to full new growth. How far can I cut the leggy branches back? And how many of them at a time? Perhaps I’m being too incremental in my pruning and not giving it the fresh start it needs. You prune in early fall, then your tree puts on a lot of leggy growth over winter, growth you’re reluctant to remove until fall. In fall, you cut off all the desirable short internodes, all the way back to the long internodes. Doesn’t that sound backward? What if you pruned in late May? You’d be removing ALL the leggy growth from winter. Then, as new growth with short internodes follows the spring pruning, you pinch until Sep, then don’t do any pruning until the following Memorial day. That approach guarantees ALL growth is the tightest the plant can produce within other cultural influences. You saw the growth explosion on the tree I pruned back to only a few leaves (above)? That’s 2 months worth of summer growth. Thoughts? Al

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