Posts Tagged: scald
Blueberries Looking Sad?
Advice From the Help Desk of the
UC Master Gardener Program of Contra Costa County
MGCC Help Desk Client: I've attached photos of our Patriot blueberry bush. Why are the leaves turning brown and curling? The problem began about a month ago. We tried to treat with acidifying powdered fertilizer, applied to the soil and cultivated in prior to watering. We water every other day or as needed (we check soil moisture with a short stick). The plant is now sending out new growth which looks relatively healthy.
Blueberriy showing sun burn/scald and/or water stress...
MGCC Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk with your blueberry question. You wrote that the leaves were turning brown and curling.
Your photographs were helpful. We think the plant has been experiencing sun scald and/or water stress. Several different factors may be contributing to this.
1. Blueberries have a shallow root system. During times of high moisture demand the roots may not be able to keep the leaves hydrated. This is especially true for container plants in full sun where during significant heat spells they will likely need water every day. To help the roots function, we recommend that you put an inch or two of mulch such as wood chips, or well-decomposed compost on the top of the soil (but keep it at least an inch away from the stems). This will help the soil to remain cool and reduce water loss.
2. Shallow rooted plants are susceptible to damage from cultivation. When you apply fertilizer or acidifier, just water it in without cultivating. Plants with damaged roots will have a much more difficult time absorbing sufficient water.
3. Shallow rooted plants need room to expand sideways in order to have an adequate root volume. We recommend that you re-pot your blueberry plant into a wider container in the fall once the weather cools down (e.g. November). Wait at least 4 weeks after re-potting before applying any fertilizer.
Additional information on growing blueberries can be found at this University of California website http://ucanr.edu/sites/gardenweb/files/29062.pdf.
I hope that this information is helpful.
UC Master Gardener Program of Contra Costa County (JL)
Note: The UC Master Gardeners Program of Contra Costa's Help Desk is available year-round to answer your gardening questions. Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA 94523. We can also be reached via telephone: (925) 646-6586, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/ MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (//ucanr.edu/blogs/CCMGBlog/).
Sun Burn to Grafted Trees
Field topworking avocados and citrus can be a prolonged process that can take two years of maintenance before the trees are productive. Often, it's easier and cheaper to just start off with a new tree. Thegrafted tree needs to be pruned back and buds or bud sticks need to be inserted into the old trunk. Birds love to sit on these new perching spots, and can often damage the bud stick, so they need to be protected with some type of covering like a paper bag. The latent buds in the trunk need to be constantly removed to prevent the old scion from outgrowing the new one.
A nurse branch also needs to be maintained so that there is a steady flow of transpired water to cool the trunk. Bud sticks are leafless and when the tree is headed back to graft, the tree no longer has the leaf area to pump water through the trunk. The trunk can heat up and result in sun burn damage. This damage may not appear for a year or so after the incident has occurred. It normally will show up on the south or southwest side of the tree, which catches the afternoon sun. The damage may be so severe that the tree dies, or the tree may begin a healing process as with other wounds and start growing callus tissue along the margins of the sun burn damage. If the damage is nor too extensive, the callus growth can eventually cover over the damage with new bark. If the grafted tree has left some structural branches, damage can show up on upper surfaces of branches, as well as those sides facing the afternoon sun.
To avoid sunburn damage, retain the nurse limb for about a year after grafting and whitewash or cover the trunk with a protective paper. Managing irrigation is important, as well. If grafted trees are interplanted with trees with more mature canopies, the grafted trees should be on a separate irrigation system and schedule. This is to avoid water stress which can enhance sun burn.
Sun burn can happen to any grafted tree, especially those with thin bark, like citrus and avocado. Any time a portion of the bark is exposed to sun that has previously been in the shade, can also set up the tree for sun burn. So excessive pruning going into summer months can also cause significant sun burn.
Sunken area of trunk, showing sun burn damage and callus growth starting to grow along margins of damage. Grafted citrus with nurse limbs and whitewash.
IMG 1956
citrus whitewashed and grafted
Too Much Water…. Bad News for Roots
Many of us think about too much water killing alfalfa during the hot days of summer. And this...