Cranberry Yellow Vine
| (photo1
and photo2):
Sample
of vines with Yellow Vine Syndrome taken from Washington County, Maine
on Aug. 25, 1999 |
Herbicide Injury (not Yellow
Vine) (photo): Cranberry
leaves damaged by the herbicide, Evital. Notice how the yellow versus green
patterning is reversed from that of Yellow Vine. |
The following is excerpted and adapted with permission
from the UMASS Extension's Cranberry
Station Newsletter -- July 2004 issue (pp 1 - 2 -- by Carolyn DeMoranville):
Yellow Vine (YV) shows up as a yellowing along the leaf
margins (edges) with the areas along the leaf veins remaining green. Usually
the symptoms show up first in the old leaves and then move up the stem
into the new growth. The most common time for the symptoms to become severe
is around fruit set when demand for resources in the plants is high and
dependence on sprinkler irrigation is greatest.
What causes YV?
The YV symptoms are most likely due to nutritional imbalances in the cranberry
plants. BUT fertilizer management is not the cause of the problem.
Instead, we believe that the nutrient imbalance is secondary to root
problems caused by stress. The
stress involved is most often water stress (too much OR too little)
but may also involve herbicide stress on some bogs. [Maine Note: Casoron
was a likely contributor for YV found on Maine beds in 1999]. These
stress conditions lead to poor root development. This past spring [2003]
many [Massachusetts] bogs stayed wet due to late ice out and frost protection.
This can lead to shallow rooting. Casoron use can aggravate the problem.
We have previously visited [Massachusetts] bogs with patches of YV and
have found that the soil water content in the YV areas is either
much higher or much lower than that in the surrounding green areas.
The consistent finding has been that the rooting depth in YV areas is
shallower than that in unaffected areas. In drought conditions, common
most years during July and August, uneven distribution of water occurs
due to reliance on sprinkler irrigation and varying distance to the underlying
water table. Put this together with the high nutrient demand during early
fruit development and nutritional problems may be the result. Fertilizer
tends to be washed away from the roots during irrigation and areas with
poor rooting may not be able to move enough minerals and water to meet
the demands of both shoots and fruit. This sets up a competition for resources
in which the
developing fruit and the youngest leaves (at the top of the shoot)
are the best competitors, leaving the older leaves showing symptoms of
nutrient stress, in this case, YV.
Treating YV -- short term fixes
YV plants are not doing well at taking in nutrients from the roots. For
this reason, adding more fertilizer to the soil most likely
will do little to arrest or reverse YV. Instead, foliar feeding should
be considered. Providing nutrients through the leaves, bypassing the roots,
can help to bring the plants back into nutritional balance. Based on tissue
testing in YV bogs over a period of years, and based on field research
and grower experiences, the most likely foliar feeds to be helpful are
magnesium (Mg) and urea. These should be used separately. If you have had
success with Mg in the past, try it first, otherwise try the urea first.
Apply at dawn or dusk (preferred) as you would a pesticide (minimize washoff).
The aim is to have the plant stay wet for several hours after the material
is applied so that it may penetrate into the leaves. Use urea at 2-4 lb/A
(to give approximately 1-2 lb/A nitrogen). For Mg applications, use a commercial
foliar feed (3% Mg) at 1-2 qt/A or apply 2/3 lb/A Epsom Salts (magnesium
sulfate). Urea and Epsom Salts should be dissolved in water prior to application
as a foliar feed.
Treating YV -- long term solutions
In the long term, changes in water management may be needed. In most cases,
YV appears in areas that were too wet
early in the season. This leads to limited root development and these
same areas are then the most susceptible to YV and water stress later in
the season. Rooting depth can be improved by keeping the bed well drained
early in the season. This is particularly important in years with frequent
frost nights requiring sprinkler operation or in years with heavy rainfall.
When the water table is closer than about 6 inches below the surface, root
development and root function is impaired. A float device, designed by
Bruce Lampinen, mounted in a perforated pipe (directions for constructing
and installing these are available from the Station)
is useful to monitor the depth to the water table and to minimize times
when the water table is too close to the root zone. Water can move up from
a water table at a depth of up to about 15 inches by the process of ‘capillary
rise’. With a water table below 15 inches, capillary rise may be unable
to keep up with plant water demands, particularly at midday under stressful
conditions (hot, dry, windy). A tensiometer can also be used to monitor
moisture in the root zone. A water table varying from 6 to 15 inches in
depth (as recommended above) will result in tensiometer readings between
1.5 cbar (at 6" water
table depth) to about 4 cbar (at 15" water table depth). Therefore,
tensiometer readings can be used to assess water status and irrigation
can be scheduled based on an early morning reading of the tensiometer.
Morning readings:
0 - 1.5 cbar soil is too wet
1.5 - 4.0 cbar adequate water is available
4.0 - 7.0 cbar adequate water for mild conditions, but if hot and/or
dry conditions are forecast, irrigation should be applied
>8.0 cbar irrigation is needed, regardless of weather conditions
Ideally, irrigation water should be applied as a combination of subirrigation
(manipulation of the water table) and overhead sprinkler irrigation.
If you have comments or questions about this page,
contact Charles Armstrong at: charlesa@umext.maine.edu
Putting
knowledge to work with the people of Maine
