Help for the Home Gardener from the Contra Costa Master Gardener Help Desk

Client's Problem:

I have a 30-40 year old pomegranate in Walnut Creek in our back yard. For the last several years we've had a very poor crop. Maybe 8-15 fruits over the whole tree. In the spring we get lots of flowers but most of them fall off the tree. This year we have ended up with 8 fruits all rather big. I don't know whether or not we are watering it enough. This might have some bearing on my problem. The tree grows lots and lots of branches starting at the lower trunk and continuing up to the top of the tree. Is there anything I should be doing?

CCMG Help Desk Response:
Thank you for contacting the Contra Costa Master Gardeners with your pomegranate question.

Although pomegranates are known to be drought resistant, they do require even moisture during the growing season to set fruit properly. Our historic drought over the past 3 years has affected many plants and trees ability to cope. How are you irrigating your tree? Are you on drip or sprinkler? Are you watering throughout the root zone of the tree or only close to the trunk? Is the rest of your yard that is close by the tree irrigated? Also, does the tree receive at least 6 hours of sun or have other trees shaded out your pomegranate over the years since it was planted? Because of the drought, the soil is very depleted of moisture, even clay soils which retain water for much longer than other soil types are often quite depleted.

Since you mentioned that the tree drops its flowers in the spring there most likely is some cause for the flowers dropping at that time. Besides wind and/or frost, the flower drop could be moisture stress because of the lack of rain earlier. Checking the moisture level of your soil at flowering time would be beneficial. Using a soil probe to check the moisture or just digging down 6 to 12 inches and checking how moist the soil is by hand are the best methods. The following website will explain how to check moisture content by look and feel. http://www.cdpr.ca.gov/docs/county/training/inspprcd/handouts/soil_moist_feel_test.pdf

Mulching your tree will also help with moisture issues. Placing 2 to 4 inches of mulch throughout the root zone of your tree is appropriate, but also provide 12" of clearance around the trunk.

You mentioned that the tree was sending out lots of branches from the lower trunk. Are these suckers coming up from the root zone or actual branches coming off the main trunk?. Does your tree have one central trunk or many trunks coming up from the ground? If the tree is spending a lot of energy making vegetative growth it may not have enough left over to spend on fruit. Removal of water sprouts and/or branches below the bud graft (if any) is also recommended. See the links below for more information on this.

You also mentioned that your tree is 30-40 years old. Some varieties of pomegranate decline after 15 to 20 years of production, although others can live for 100+ years. Most slow down production in the 20-25 year range.

It appears that it may be several reasons for your lack of fruit production. Drought conditions, lack of irrigation and age of the tree being the most likely.

For more information on Pomegranate care please refer to the following websites, including an online book on pomegranate care.
http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/pomegranate.html
http://ucanr.edu/sites/Pomegranates/files/164443.pdf

Hope that information helps you. Please feel free to ask more questions if need be. Best of luck with your pomegranate tree.

Contra Costa Master Gardeners Help Desk 

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Editor's Note: The Contra Costa Master Gardener Help Desk is available year-round to answer your gardening questions.  Except for a few holidays, we're open every week, Monday through Thursday 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, and we are on the web at http://ccmg.ucanr.edu/

 

Having lived most of my life in the Pacific Northwest, my frame of reference for the gardening season was this: in the spring, gardens were planted, then from May until September, things would grow, berries were picked, various crops were harvested, apples and pears ripened, pumpkins and other gourds were ready for Halloween picking, and then it was done. The gardens were shut down and left fallow for the winter. It was a very finite time, and unless someone was that rare warrior gardener willing to take on cold frames, ice and snow, and freezing temperatures, gardening ceased until the spring, when the cycle would begin again. Once the weather turned in early October, residents hunkered down to eight months of cold, wet and rainy weather (27 to 48° F, and 78.63 inches of rain, give or take a tenth of an inch).

Contrast that against Contra Costa's winters of coolish days sandwiched between cool mornings and crisp evenings. Today's temperature is a high/low of 65°/46° F.  For some of us that live here, its feeling a bit nippy and we want to wrap up and hunker down inside like our Oregon counterparts (to a Portlander, though, 65° is considered balmy, and a great excuse to wear shorts; its not unusual to see Portlanders walking around with shorts, boots and a down vest in the winter).

Although it's understandable to want to hunker down and wait until early spring to begin the garden, we have perfect weather for growing cool season crops. In many ways, a cool season garden is easier to tend to than a warm season garden because:

• There are fewer insects to contend with;
• Watering needs are much lower this time of year; and
• The plants can withstand light to hard frost and temperatures down to 28° F.

My garden currently contains Romanesco, broccoli raab, and cauliflower. I grew them successfully last year, along with some spinach and lettuce varieties, and I am looking forward to enjoying them again this year.

The Romanesco is a vegetable that I hadn't heard of until last year, and I am enthralled by it. It's not only a delicious-tasting vegetable, but also a beautiful work of art, with its vivid lime green color and perfectly spiraled fractals. It is known as either Romanesque Cauliflower or Romanesco Broccoli, and is of the Brassica oleraceaspecies.

If you haven't tried a Romanesco yet, here is a recipe for Broccoli Romanesco with Sage Browned Butter for you to try, hoping that once you taste it, you'll want to grow it.

Romanesco starts are available at local nurseries. Our Garden in Walnut Creek offered Romanesco veggie starts for sale this year before the end of the season.   Look for them again next year.

Other plants that do well in the winter/cool season garden are:

Light Frost Hardy (as low as 32° F). Artichokes, beets, carrots, cauliflower, celery, chinese cabbage, endive, lettuce, parsnips, peas, swiss chard, escarole, arugula, bok choy, mache, and radicchio.

Hard Frost Hardy (as low as 28° F). Broccoli, Brussels sprouts, cabbage, collards, kale, kohlrabi, mustard, onions, parsley, peas, radishes, spinach, turnips, leeks, and sorrel.

 

 

Help for the Home Gardener from the Contra Costa Master Gardener Help Desk

Client's Problem and Questions:
Client called (early September) and left a phone message that the her community garden colleague's tomatoes, although now 4 feet tall, set some fruit, but that the plant had suddenly started to turn yellow and appears that the plants won't surive. CCMG Help Desk responded with both a phone call and an email.

CCMG Help Desk Response:
As I mentioned in the phone message that I left for you this morning, the information in your phone message about the tomato problem your community garden colleague has experienced wasn't sufficiently detailed to allow us to diagnose the problem. You mentioned that the tomato had grown about four feet tall and had set some fruit, but that the leaves on the plant suddenly started turning yellow and it now appears that the plant won't survive.

Yellow leaves on tomatoes is associated with many different problems, including lack of nutrients, excess salts in the soil or in irrigation water, toxicity in the soil from nearby walnut trees, and many different plant diseases. You report that the plant had been growing well and producing fruit and declined very rapidly leads me to suspect that the cause may have been a vascular wilt disease.

Two such vascular diseases are common in California gardens—Verticillium and Fusarium wilts. The initial symptoms of Verticillium and Fusarium wilts are wilting of the plant leaves during the heat of the day. Affected plants often recover in the evening or overnight. Gradually, however, the wilting becomes progressively worse and many plants eventually die. Verticillium and Fusarium wilts are caused by soil-borne fungi that invade tomato plants through injured roots. The fungi spread into the water-conducting tissue (xylem) in the stem and block the flow of water to the foliage. Foliage of affected plants turns yellow, then wilts and dies. A cut through the lower stem of a dead plant often reveals a brownish discoloration of the vascular tissue. If your colleague will allow you to investigate, you might try cutting open a lower stem to see whether the tissues inside the stem are a healthy white color or have turned brown. If they have brownish discoloration, it would be a sign that a vascular disease is present. If the vascular tissues have not discolored, there is probably a different cause for the plant's decline.

There is nothing that can be done for plants that have Verticillium or Fusarium wilts. Plants that die should be removed and destroyed. Put the diseased plant refuse in the garbage. Don't compost it since doing so could contaminate the compost with the fungal spores. Crop rotation is of limited value as the vascular wilt fungi may survive in the soil for several years.

Verticillium Wilt Infected Tomato

The use of resistant varieties is the most practical way for home gardeners to prevent losses due to wilts. Resistant varieties may become infected but many resistant plants survive and produce an acceptable crop. Resistant varieties are available in seed catalogs and at garden centers. The letters V and F following the variety name in seed catalogs or on seed packets denote varieties that are resistant to Verticillium and Fusarium wilts.

You can learn more about Verticillium and Fusarium wilts at these websites:  http://www.ipm.ucdavis.edu/PMG/r783100911.html  and http://www.ipm.ucdavis.edu/PMG/r783101011.html.

One other word of caution about something you mentioned in your phone message. You indicated that you are using free wood chip mulch from a tree service company in your community garden plot. You said that your plants are growing well and look beautiful, but you didn't mention whether you are growing vegetables or ornamental plants. We don't recommend the use of wood chip mulch in vegetable gardens. Using such mulches for vegetables leads to two different problems. One is that wood chips, if dug in, and as they haven't been fully decomposed, will rob much of the nitrogen from the soils. This depletion of a critical nutrient can affect some ornamentals. It is particularly a challenge for heavy feeders such as tomatoes. If your colleague was using wood chips as compost for her tomatoes, it's possible that one of the problems for her tomatoes was a lack of nitrogen which would also lead to yellowing of the leaves.

The other problem with using wood chip mulch in vegetable gardens is that such gardens need to be replanted after each growing season. The wood chips really get in the way when you're trying to prepare the planting beds, add compost, etc. It is not a good idea to simply work them into the soil since they will continue to decompose, using up the available nitrogen in the process.

A better mulch to use for vegetable gardens would be weed free straw or dried leaves.

Hope that this information is helpful to you and your colleague.

Contra Costa Master Gardeners Help Desk 

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Editor's Note: The Contra Costa Master Gardener Help Desk is available year-round to answer your gardening questions.  Except for a few holidays, we're open every week, Monday through Thursday 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, and we are on the web at http://ccmg.ucanr.edu/

Help for the Home Gardener from the Contra Costa Master Gardener Help Desk

Client's Question and Problem:

Client left a message on the Help Desk telephone. Client is growing two tomato plants and some pepper plants in containers. While they have produced fruit, but most of it is still very green (as of early September). You wanted to know if there was something you could do to speed up the ripening process. CCMG Help Desk responded by email.

CCMG Help Desk's Response:
I'm writing to respond to the questions that you left in your Help Desk phone message. I understand that you are growing two tomato plants in containers as well as some peppers. You mentioned that the tomatoes have produced fruit, but most of it is still very green (as of early September). You asked whether there is something you can do to speed up the ripening process.

You probably won't be able to speed up the ripening of the tomatoes. The timing of getting ripe tomatoes depends both on when you started the tomatoes and on the variety you are growing. In my own garden, I planted eight different heirloom varieties this year. Two of them are in pots. I planted seedlings from four inch pots in early April. Most of the tomato varieties starting giving me quite a few ripe tomatoes by late July. However, one of them only produced an occasional ripe tomato until about a week ago, when I started being able to harvest three or four ripe tomatoes per day. The two tomatoes I have growing in containers are likewise producing ripe tomatoes at different rates. One has produced many ripe tomatoes and only a few green ones remain on the plant currently. The other was much slower to start producing ripe tomatoes. I've picked quite a few of them, but it still has lots of green tomatoes which I know will continue to ripen over time.

So my advice is just continue to be patient. For earlier tomatoes next year, you could pick a variety that produces early fruit. Or, if the weather cooperates, you might be able to plant your containers somewhat earlier next year. (I generally wait for night time temperatures to regularly reach 50 or above before planting. That target temperature occurred somewhat earlier this year than it does in many years.)

As for your question as to why your pepper is producing green peppers when the variety is supposed to be red, again the answer is that you'll just need to be patient and wait a while longer. All pepper varieties start as green peppers. With time, varieties that produce other colors will begin to ripen and change color. It sometimes takes several weeks after the green peppers have developed to their full size before you will start seeing a color change.

Both peppers and tomatoes can easily be sunburned. The sunburned area turns a light brownish color. It's still fine to eat the fruits, but you generally have to cut out the sunburn. To prevent your green tomatoes and peppers from getting sunburned, try to be sure that the developing fruit has some leaf cover. If not, you can also erect some type of sunshade to keep the sun from scorching the fruit.

Finally, as we approach fall and cooler temperatures, you may find that the ripening process slows. I generally leave my tomatoes in the garden if they still have green fruit until the night-time temperatures start to dip into the 40's. Tomatoes are quire cold sensitive so the plants will start dying when the weather cools. At that point, I harvest all the green tomatoes and put them on my kitchen counter. They will continue to ripen there. The fruit that ripens that way isn't as wonderful as a vine-ripened fruit, but it's still better than what you can buy in the grocery store. Unfortunately, peppers won't change color after you harvest them, but the green colored peppers can be just as tasty as those that have taken on their ripe color.

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A post script...

I hadn't realized from your phone message that the main question you have is “Why has the ripening of the tomatoes slowed down so much from what it was in prior years?” Thanks for clarifying.

Here are a couple of possible causes.

• A key resource that tomatoes need for ripening is plenty of leaf surface for photosynthesis. Often by late summer, some of the leaves on the tomato have started to dry up and wither and are no longer helping to nourish the plant. The plant is less vigorous than it was earlier in the season so it takes longer for the green tomatoes to ripen.
• High temperatures are also a major cause of slow ripening. The tomato plant produces several compounds that are needed for tomato ripening. When the air temperature rises above 85 degrees, tomatoes stop making carotene and lycopene pigments, two of the most important components in the ripening process. We have had some recent hot weather spells which are probably affecting your tomatoes in this manner.
• Finally, soil temperatures are also important. For optimal growth, tomatoes need soil temperatures that are less than 80 degrees. Hot air temperatures raise the soil temperature. Containers may be particularly vulnerable to soil temperature rise if they sit in the hot afternoon sun. Mulching can help keep soil temperatures lower. Also, if your tomatoes are hit by afternoon sunshine, you might consider erecting some shade barriers to keep the sun off the containers.

If you've run out of patience with slow ripening tomatoes, one thing you can do to speed up ripening is to remove some of the green tomatoes. Then the tomato plant can put all its energy into ripening the tomatoes that remain on the plant. You can ripen the green tomatoes you remove on your kitchen counter. As I responded earlier, they won't be as yummy as the ones that ripen on the vine, but they're still better than store bought tomatoes.

As a final caution, don't be tempted to fertilize the tomato plant thinking it will speed up production. Fertilizing now will probably just cause the tomato to go into a vegetative growth mode that is too late in the season to be helpful.

Hope the above explanations clarify what is occurring. You're welcome to contact us with any additional questions.

Contra Costa Master Gardeners Help Desk 

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Editor's Note: The Contra Costa Master Gardener Help Desk is available year-round to answer your gardening questions.  Except for a few holidays, we're open every week, Monday through Thursday 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, and we are on the web at http://ccmg.ucanr.edu/