Checklist for flood recovery - grapevines
Note number: AG1423
Published: March 2011
Following flooding or waterlogging of grapevines there are a number of key issues that need to be addressed.
- The full impact of flooding will not be apparent for some time after the event.
- Ongoing monitoring is important to manage vine health and identify issues.
- Flooding may also cause leaching of nutrients, loss of mulch material and crusting (slaking and dispersion) of the soil, and these effects will require management.
Grapevines require a supply of carbohydrates from stored reserves to support new growth in spring.
- The period following harvest is an opportunity for translocation of carbohydrate and nutrient reserves into permanent structures for the vine to start the growth phase for the next spring.
- Providing leaves are still green and the supply of water and nutrients are adequate, the vine is able to accumulate and store carbohydrates for use in the next season.
- There may also be a period of root growth if harvest is not too late and the weather remains warm.
- In warmer regions, temperatures may be sufficient to allow photosynthesis for an effective period after harvest.
- If leaves are lost (due to disease) or cold weather brings a premature end to the post harvest period, then photosynthesis and accumulation of nutrients will not occur.
- Heavy rainfall and flooding can cause nutritional problems, for example, nitrogen, potassium and boron are prone to leaching and levels are likely to be reduced.
What should I do?
Assess whether conditions are suitable for nutrient and carbohydrate accumulation, that is, there is good leaf cover and leaves are still photosynthesising:
- Post harvest fertiliser applications should be adjusted to make up for any envisaged losses due to flooding.
- Adjust fertiliser rates carefully as over application should also be avoided.
- Once water has drained and if the soil dries out, irrigation should be scheduled carefully to allow for possible impaired root function due to waterlogging.
- It will be essential to undertake petiole analysis next season when vines are flowering to tailor fertiliser applications to need.
- It is also advisable to carry out a soil test.
Soil and root health
- Some soils, especially those with a high clay content, can become compacted and form a surface crust after heavy rainfall and flooding.
- Driving machinery on wet soils will also compact the soil – minimise driving on wet soil.
- Flooding, following years of drought can significantly increase the risk of soil salinity and sodicity (high levels of sodium) if drainage is poor.
- In addition, saline groundwater levels can rise to the soil surface or the root zone during wet weather and flooding and damage vine roots as the soil dries.
- Calcium added to the soil restricts sodium adsorption by soil particles and avoids the degradation of soil structure.
- Root rots may not be apparent in autumn as the vine shuts down for winter. Monitor areas in spring that remain waterlogged for extended periods for symptoms of root rot, e.g. slow early growth or die-back of shoots after budburst.
What should I do?
- If the soil has set hard, once it is dry (at field capacity) a "one-off" light cultivation may be desirable to break up the compaction to allow water and oxygen to penetrate.
- Look for symptoms of salt affected plants.
- Determine the salt levels in the water table, by installing test wells and sampling, sampling water from drains or using extraction tubes.
- Gypsum added to the soil or dissolved in the irrigation water will displace and restrict the attachment of sodium to soil particles.
- A dispersion test should be carried out prior to application of gypsum to determine the requirements.
- Consider installing drains to remove excess water from waterlogged areas.
- An organic mulch, e.g. straw, spread on the vine line will reduce crusting and improve water penetration, aeration and drainage of the soil profile.
- Farmyard manure and organic mulches applied to the vine line can encourage beneficial organisms.
- It is important to establish cover crops to help recover soil structure and build up organic matter.
- Get cover crops in as soon as possible.
- If the permanent sward has been killed off by flooding it is desirable to re-sow over the coming autumn and winter.
- Vines should be monitored closely for increased presence of fungal diseases.
- Cultural management techniques to minimise the outbreak of diseases should also be considered, e.g. crop load adjustment, leaf plucking, canopy topping, and bunch thinning (do not damage bunches).
- Following the floods and waterlogging it can be expected that there will be increased disease pressure next season.
- It will be essential to monitor the vines closely for early signs of disease next season and effectively manage disease issues.
- Review the 2010-11 season disease management strategy and include any suggested improvements in the next seasons disease management plan.
- Diseases and loss of leaves may impair cane maturity. Frosts will kill any immature portions of canes.
- If using cane pruning, check that the full length of cane retained is viable – the internal section of the cane should be white-slightly green and not brown.
- The basal portion of longer canes should be sufficiently hardened to provide viable spurs.
Adem, H. and Schache, M (2011) Management of Salinity Arising from Flooded Orchards and the Use of Bore Water, Note Number: AG1439, DEPI, Victoria.
Dimsey, R., Whiting, J. and Adem, H. (2011) Managing Crop Recovery After Flooding – Grapevines, Note Number: AG1435, DEPI, Victoria.
Correct diagnosis is essential for effective pest and disease control. A commercial diagnostic service is available at the AgriBio Bundoora.
For further information, phone Crop Health Services on (03) 9032 7515.
For further information on registered chemicals, phone our Customer Services Centre on 136 186.
This Agriculture note was prepared by Rob Dimsey and John Whiting, Farm Services in March 2011.