Ah yes… summertime ! Warm sunny days, light breezes and DODDER !!!
A tangle of dodder !
What is it?
Cuscuta (dodder) is a genus of over 201 species of yellow to orange parasitic plants that look like angel hair pasta! It is in the morning glory family – the Convolvulaceae (morning glory) – and found mainly in warm tropical regions. Here in NY it is an occasional summer problem – especially on soft herbaceous annuals and summer tropical plants.
Although it’s a flowering plant – it has no leaves, or roots ! It attaches itself to a host plant via a root like structure called a haustorium – which is quite alien like. As a parasite, it doesn’t produce chlorophyll or make its own sugar. It simply takes what nutrition it needs from other plants. That is why it is never green !
Small white flowers on mature stems of Dodder
Flowers and Seeds
It has really small flowers and even smaller seeds. Tiny white, bell-shaped flowers are borne in clusters followed by small rounded fruits or seed capsules. It is prolific ! – one plant can produce thousands of seeds. Dodder seed is used medicinally in Asia.
Seeds disperse easily and come back in your garden next year when the summer warmth arrives. These can also survive in the soil 20 years or more. They are spread through the movement of soil and equipment, in infested plant material, or as a seed contaminant.
Life cycle
It germinates like other plants but then immediately seeks a host. It has a few days to do this or its dies. Once it finds one it wraps itself around the victim and lets’ go of its own roots! The now totally dependent vine creates a sticky glue that it uses to secure itself on to a stem. It then forms the special structure (haustorium) that protrudes into the tissue and blends its own vascular system with the victim’s. It pulls in sap and nutrients by keeping its own stomata (breathing pores) open 24/7 creating a pressure gradient – a flow – to pull the sap into its own.
The Haustorium (center) invades the host’s(left) vascular tissue!
Once it gets going it takes over the host plant and although may not kill it – it certainly weakens it plenty! Annuals or summer tropical that get dodder rarely ever bloom properly. Not to mention you cant hardly see them through the tangle of fine dodder threads! It even attacks Euphorbea which has sticky toxic white latex sap !
The plant is killed by frost and has to re-establish from seedlings each year. In temperate areas it is only found in relatively low vegetation, whereas in tropical areas, it may reach high into the canopy of shrubs and trees.
A tree in the tropics covered in Dodder.
What can you do ?
Well aside from using some nasty weed killer – not much in terms of chemicals. Prevention and cleanliness is the only long term solution. You can prune or clip it significantly below the infestation – just don’t leave a speck – it is able to grow back from its haustoria. If not possible, then discard the entire host plant.
If you leave a little piece of haustorium inside the host – the Dodder will grow back ! Burn it baby ! Any plant that had dodder probably has seeds in the soil that will sprout next year. So a complete renewal of mulch and soil is recommended. Dodder seeds are fine like dust!
You can use plants not susceptible to attack by dodder, such as grasses and lilies.
OR – keep the pretty annuals and just hire a Plant Specialists gardener to do all the watching for you !
Call Plant Specialists TODAY !
Don’t delay – the sooner the better !
GREENING NEW YORK FOR OVER 51 YEARS !
Article written by our Staff Horticulturist, Peter B Morris, BSc, MSc, MBA
All photographs used with permission @SHUTTERSTOCK
