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OUT IN THE GARDEN AGAIN – TOMATOES AND BUTTERFLY BUSH

written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

Local gardeners are complaining about their tomatoes. In some cases the tomato plants are failing to thrive and then start to die. I haven’t been able to pinpoint a central cause, but there are several possibilities. One simple problem may be that the roots weren’t spread at planting time and the root ball was kept ‘pot bound’ once planted in the garden. Now that the plant is bigger and there are more demands on it from hot temperatures and wind, the restricted root system isn’t adequate to support the top of the plant. Gardeners should first check the roots of plants that don’t seem to be thriving and have stopped growing.

Verticillium wilt is another possible cause of the problem. Verticillium wilt is a fungus disease that lives in the soil and enters a plant through the roots. Attacked plants wilt and develop stunted growth with yellow leaves that have a tendency to roll inwards. The yellowing shows up first on the lower leaves. These leaves later turn brown and die. The fungus works by plugging up the water conducting tissues in the stems, resulting in symptoms that at first resemble drought. While older plants may not die outright, they will suffer from poor growth and yield. Younger plants often die.

There is no chemical control for the disease. Management of the disease involves making sure to rotate garden crops. Don’t plant verticillium susceptible veggies (tomatoes, potatoes, peppers, and eggplant) in the same area every year. There are also verticillium wilt resistant varieties (indicated with a ‘V’ in seed catalogs or on plant tags). Another good idea is to control any weedy hosts of the disease around the garden, such as nightshade.

Curly top virus is another disease problem that is probably one of the causes of local tomato woe. It’s a virus disease that attacks tomatoes, as well as a number of other veggies and annual flower crops. The first symptoms are puckering and upward rolling and twisting of leaves. As the disease progresses, the entire plant starts to turn yellow. Leaves become thicker and take on a more leathery texture. The veins usually take on a purple hue. Younger plants are often killed by the disease, but older ones become stunted and unproductive.

There is no chemical control for the disease. If infected, you should pull out and dispose of the infected plants. Preventing the disease by controlling the leaffhopper that infects the plants with the disease is also not effective. When it comes to tomatoes, there are several resistant cultivars. These are

Columbian

,

Rowpac

,

Roza

, and

Saladmaster,

but their availability is limited. It’s recommended that you don’t plant tomatoes near spinach or beets. You may also want to try shading your tomato plants with taller crops, as leafhoppers avoid feeding on shaded plants.

Another problem showing up on tomatoes in some gardens is not too serious. It’s called blossom end rot and it causes a dark, leathery lesion or blotch on the ‘blossom end’ or bottom of the tomato. Despite its name, blossom end rot is not really a disease. It’s a physiological-nutritional problem brought about by a lack of calcium reaching the developing fruit. However, it’s not caused by a lack of calcium in local garden soils.

Blossom end rot is usually brought about by watering problems. Moisture is needed in the soil so that roots can absorb the calcium needed for developing fruit. If the soil is too dry, the roots can’t take up calcium. If it’s too wet, the roots can’t function well and also can’t take up calcium. High temperatures and root damage can also be part of the problem. The key to avoiding blossom end rot is careful watering and keeping the soil evenly moist. It also helps to mulch the plants with an organic mulch of some sort. Avoid fertilizing heavily and be careful to only hoe weeds at the surface, as deep cultivation can damage the roots.

Elsewhere in the garden… it’s so nice to have a trouble-free flowering shrub that blooms in the summer, attracts butterflies, and smells nice too. Butterfly bush (Buddleia davidii) is a plant that many area gardeners have included in their landscapes. The traditional butterfly bush has showy purple spikes. More recently the nursery industry has introduced white, yellow, pink, blue, red and orange flowered forms.

Butterfly bush is drought tolerant, adaptable to many different soil conditions, does well in hot weather, and attracts butterflies and hummingbirds. It has so many good points, it’s been recommended by many, including me. However, now we’re learning that it might not be desirable. Butterfly bush has become a weed problem in other countries and there is concern that the same could happen here in our state. In countries like New Zealand, it’s crowding out native species of plants. The concern is that the same thing could happen here in Washington, particularly in western Washington riparian areas, forests, pastures, and roadsides where it can form dense thickets.

The characteristics that make it an easy-to-grow shrub, also help it to out-compete native vegetation. The shrub produces millions of seeds per plant that are spread by wind and water. Plants that develop from seed can reach maturity and start flowering within one year. When cut down to the ground, the shrub easily resprouts from the roots. It does sound like a potential nightmare and that’s why the Washington State Noxious Weed Control Board has placed butterfly bush (Buddleia davidii) on the state’s noxious weed list as a ‘Class C’ weed. ‘Class C’ weeds are non-native weeds that pose a possible threat to native habitat.

Responsible gardeners may want to think twice about planting butterfly bush, if they haven’t already. However, if you’re a gardener who already has a butterfly bush you can minimize the threat they pose:

– ‘Deadhead’ or prune off all the dead flower spikes. Dispose of the flowers in the garbage, not in the compost where the seeds might survive. Don’t ever dump the clippings or leave them on the ground so that the seeds can spread.

– Prune back your shrubs every winter to keep them smaller and easier to deadhead.

– Plant other hardy species of buddleia. So far, these haven’t been weedy problems elsewhere.

To find out more about weeds and weed control, visit the Washington State Noxious Weed Control Board’s website at http://www.nwcb.wa.gov or call them at 360-902-1901. You can also contact your local county noxious weed board. In Benton County call 943-6005 and in Franklin County call 545-3847.
Published: 7/23/2005 11:45 AM

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