Horticulture Guy

Q. I planted blueberry plants in the spring, they have been doing well, up until recently. The berries that were on the plants when I purchased them ripened, there’s new growth and some of them are flowering again. Recently, however, the leaves have begun to curl under and are starting to turn slightly yellow. The plants are planted in full sun on the south side of house in a bed against the house, soil drains well and when I planted I added miracle grow and composted steer manure. As the weather grew hotter in addition to the morning sprinkler system, which runs 15 minutes every morning, I would give them hand watering in the early evening. I also added some coco husk mulch. The ground isn’t dry, but not really wet either. Can you please advice what might be going wrong with the blueberry plants as I don’t want to loose them. Thanks, Mark Williams - Bellevue, WA

A. Since the symptoms you have described seem to be isolated to the leaves I suspect that you are seeing an iron deficiency in your blueberry plants. Iron is important in many important plant cell processes including being parts of various enzymes (acting as catalysts) and in the formation of chlorophyll. The symptoms of iron deficiency show up on new leaves since because it can’t be moved from older leaves to support new growth. Leaves will start to yellow between the veins and eventually curl and eventually turn brown. Although iron may be present in sufficient quantities in the soil it may not be available to the plants. Soil pH and specific plants ability to absorb iron determine how easily iron can be absorbed by plants. Blueberries prefer acidic soils because like other plants that have evolved in acidic soils they have difficulty extracting iron from the soil when the soil pH is high. Blueberries prefer a pH between 4.5 and 5.2. If you test your soil for the pH (alkalinity/acidity) you will likely find that it is much higher than 5.2. Your soil may be even have a higher pH next to your house since there is often leaching from cement which has limestone as an ingredient. I have also seen foundations of homes backfilled with pieces of old broken cement and covered with topsoil. This increased the alkalinity of the soil and effected foundation plantings of rhododendrons which are similar to blueberries in their preference for acidic soil. In the short term you can apply a fertilizer with chelated iron (the mineral is bound to a carrier which makes it available to the plant roots even in alkaline soils). Instead of the Miracle grow you have been using it would be better to use MirAcid which has chelated minerals (like iron) especially for acid loving plants like blueberries. Long term you will need to add some form of sulfur to reduce the pH of the soil. The amount you will need to apply will depend on the difference between your actual pH and your target pH of 5.2. You can use a simple Soil Test Kit to determine your soil’s pH

-- HG

Q. What is chewing on my dahlias and leaves little black specks all over? JoAnn Bernovich - Federal Way, WA

A. For those readers enjoying their Saturday morning breakfast as they read this column, I urge you to skip over this answer until you finish eating. You have been warned. I believe that the little black specs you are seeing are the fecal pellets of the offending insect. My first guess is that it is earwigs, but I always hate to blame them since they are not always the culprit but they I do know that they leave behind visible fecal pellets. The other suspect is the spotted cucumber beetle. If you see no insect activity during the day then it is more likely earwigs that are active at night. You may find the earwigs hiding inside the folds of the flowers during the day or in the soil below under a twig or such. The spotted cucumber beetles are active during the day and you should have noticed them. Both can be controlled with a pyrethrum based (powdered flower of the painted daisy - Chrysanthemum coccineum) organic pesticide like Safer Yard and Garden. If spraying during the day for earwigs you will also have to spray the soil below where they are may be hiding during the day.

-- HG

Q. Hi Peter, I usually plant a Nantes-type carrot for their wonderful snappy, fresh taste. I’ve noticed that, year to year, they have varying degrees of sweetness/bitterness to them. Mostly they are as sweet as you’d expect from a Nantes. I’m wondering if there is something I am doing to effect their sweetness/bitterness? I only use an organic type fertilizer worked into the soil at sowing time. Thanks again, Henry Raynor - Puyallup, WA

A. Carrots quality is often based on their sugar content, but as you mention sometimes they are sweet and sometimes bitter. The two key factors in carrot taste are volatile terpenoids and free sugars. Carrots taste bitter when volatile terpenoids are not balanced with sufficient sugar. Much of carrot breeding goes into influencing the genetic part of the equation. So some varieties can be sweeter because of their genes. As you have witnessed even in one variety you can find differences from year to year. Carrots can store their reserve energy in the root system in the form of starch or sugar. Starch is formed when two or more sugar molecules are combined. When the starch molecule then can be split again to release the sugar. Carrots growing in temperatures above 70 tend to form shorter, thicker roots and have less available sugar. This is because respiration is higher in warm weather so the carrot tops are using up the free sugar so it does not accumulate. In cool weather respiration is lower and more free sugar remains in the root. Optimal temperatures are between 60 and 70 degrees for sweetness. Carrots are biennial and after the first year they change gears from starch accumulation and initiate the flower bud, which also increases the sugar levels as starches are converted to sugars but are not yet used. Cold weather is the signal to the plant between the first and second year of growth. This is why carrots harvested in late fall and early winter (like for Thanksgiving or Christmas) can be sweet. Carrots can also grow sweeter in cold storage. I have also seen research that shows high nitrogen and potassium levels in the soil can also reduce the sugar in carrots. So as you can see there are many factors that can influence the taste of your carrots as the genes of the carrot interact with the environment.

-- HG

Q. What is that new mole poison that is shaped like a worm and where can I get it? Thanks. Jerry Langston - Auburn, WA

A. The product you are describing is called Talpirid. It uses the rodenticide Bromethalin (a neurotoxin affecting cell regulation of water) packed in what is for all intents and purposes a gummy worm. This has been shown to be the first effective bait format for moles since it emulates a major food source for the animal. It is toxic people (children), dogs cats and wildlife so it must be applied by a certified pest management professional and is not available to the general public. The product is manufactured by Bell Laboratories. More information is available on their website http://www.talpirid.com/. Havahart makes a mole control spray which is non toxic.

-- HG

Q. We planted a mock orange in the south-east corner of the house three years ago. It gets sun until late afternoon. Although it has grown to over six feet and looks very healthy, it has never bloomed or shown signs of bud. It has not been pruned other than an occasional munching by deer. Can you tell us what’s wrong and how to encourage it to bloom. M. M. Crettol - Olympia, WA

A. I will assume that you are talking about the Mock Orange of the Genus Philadelphus since there are some other genera that use this common name. Most Mock Oranges have wonderfully fragrant flowers so I can see why you would be anxious. These plants bloom on old wood. This means that the flower buds form the year before they bloom. So there is a chance that the deer browsing is removing flower buds and this is why it has not bloomed. Protecting the plant from browsing is one way to see if this is the problem. There is also the chance that it has not started blooming. There are straight species and hybrids (usually between species) of Mock Orange commercially available. The hybrids tend to bloom at a younger age than the straight species – sometimes in the container. So it is possible you have a straight species, in which case you would just have to be patient. The southeast exposure you mention should allow for the shrub to get enough light unless other trees obstruct them. Too much shade could also reduce or prevent flowering. Sometimes high soil fertility can also keep some mock oranges in a vegetative state since they are usually native to lower fertility rocky-scrubby slopes.

-- HG

Q. Dear Pete: My wife and I planted vine maples along the east and west sides of our home in 2003. We are unable to comprehend why the leaves of two of three trees are turning orange prematurely (before fall). Is there some way to determine if they are suffering disease or simply individuating (like teenage children)? The photos attached show: Two vine maples are on the east side of the house. The southernmost tree is orange. The northernmost tree appears green and healthy. The third tree, on the west side of the house, isn’t very leafy and what few leaves it has are orange. Do trees have receding foreheads? I don’t know how to discriminate soil-based issue vs. fungus vs. disease. I’d like to keep these trees. Any ideas? Thanks for your prompt response. Sincerely, Charles Mann - Tacoma, WA

A. I am sorry to say that Jung won’t apply in this case because your Vine Maples (Acer circinatum) are not individuating but rather indicating. But without some detailed observation it is difficult to say what problem is being indicated. The general term for what you are describing is called Maple Decline. There is some detective work that goes into the diagnosis and I can give you some clues as to how to narrow it down. You may be best served hiring a professional certified arborist to verify the problem. The first thing to consider is drought. These plants trees prefer moist soil especially if they are in full sun. They can get by with less soil moisture when they are shaded. If the all three trees are getting adequate water during our dry summer then the next possibility is root girdling. Root girdling can occur if the trees were grown too long in a small container the roots being to wrap around the sidewalls. If these roots are not pulled apart, scored (slicing outside of root ball with a knife) or otherwise manipulated out of this pattern they will continue to circle and enlarge. Over time this will slowly “choke” the tree to death. The way to check this is to slowly excavate (think like an archeologist) soil away from the base of the tree for several inches. You can use some water from a spray bottle to help clean away soil for a better view of the roots. At this time you can also be looking for signs of disease. Start from the trunk and work your way down to the exposed roots looking for loose bark, cracks or fissures, discoloration, oozing. This would indicate a collar rot / basal canker which is a fungal disease. If you find girdling roots consult a certified arborist to see if it is feasible too surgically remove the offending root(s). If you see symptoms of disease there is currently not a cure but there are measures you can take to help the tree fight this off. One is leaving the base and root collar (where the main roots meet the trunk) exposed so that the base of the tree stays dry. Keep the trees well watered periods of low rainfall. Other causes of maple decline can be physical injury from a lawn mower or string trimmer, herbicide injury, or soil fertility problems to name a few. Again a certified arborist is trained to narrow down the possibilities systematically.

-- HG

Q. HELP!! I planted my pumpkins the end of March as we were going to be gone all of April. NOW they are almost “done”. What should I do?? Leave them on the vine or harvest when they look ready? Since it is only August I am afraid they won’t last until the end of October. Dee Dee Abolins - Edgewood, WA

A. You can leave the pumpkins on the vine after they have turned completely orange. Harvest before frost is always a good idea but frost will not be a threat until October so this is not an issue. I would suggest lifting the pumpkin and placing a shingle or a similar object to keep the base of the pumpkin dry and away from the soil to prevent rotting from the base and insect damage from below. When you do harvest them make sure you cut the stem with sharp pruners. If the stem pulls away from the fruit you should immediately make pumpkin pie (or your favorite use) since the pumpkin will rot quickly through this opening. When you harvest them, store them in a cool, dry, frost free location like a garage where temperatures average around 50 degrees.

-- HG

Q. I have a common houseplant I believe called corn plant. It bloomed several months ago – photos enclosed. The flower had a deep lily-like fragrance that was very intense in the evening. It has now withered to a barely noticeable stalk. Do I leave it or cut it? Will it bloom again? Janine Carpenter - Enumclaw, WA
A. I watered many a Corn Plant (we called them Mass Cane) in my first job out of college as the “Gunga Din” of indoor landscaping. This houseplant is perhaps even more common in office buildings than it is in homes. From time to time I would see them flower. These were generally healthy large (older) specimens that were kept in moderate light conditions usually indirect natural light. The plants are popular in the indoor landscaping industry because they are tolerant of low light conditions. I say tolerant because in my experience the specimens at the bottom of a basement stairwell existing on the glimmer of a recessed incandescent bulb rarely thrived, rather they desperately clung to life. The fact that your corn plant has bloomed indicates that the plant has reached maturity and is in good health. The botanical name of the Corn Plant is appropriately Dracaena fragrans (Fragrant Dracaena). The name Mass Cane comes from the yellow striped cultivar named ‘massangeana’. Your description of the lily-like fragrance is spot on since they are lily relatives. They belong to the Agave family (Agavaceae), which was split off from the Lilly family (Liliaceae) many years ago. In its native Africa or in mild areas of the country (where temperatures rarely get below 55 degrees) these plants will flower in the summer. Since the fragrance is strongest in the evening I would guess that they are dependent on night moths for pollination. Since there were no insects to pollinate your flowers the orange berries did not form. You can simply remove the flower stalk at its base. You should see new growth from that area later on. Since your Corn Plant bloomed once it should bloom again around the same time next year if the growing conditions stay the same.

-- HG

Q. Hi, We enjoy your column and your helpful information. We would like to see you discuss the pros and cons of weeding with a blowtorch. We have seen people doing it. Can it be done in areas where you have landscape paper and bark surrounding plants you wish to keep? How about in areas where there is landscape paper covered with gravel? Landscape paper, as we know, does not keep out all the weeds. Thanks for the information. Dick and Jan Swanson - Olympia, WA

A. Blow torch weeding is essentially has evolved into a long handled tool that connects to a propane tank and allows the use of heat to scorch and dehydrate weeds. Many people think that the goal is to burn up the weed. The objective is the have the flame close enough to allow the flame to heat up the air surrounding the weed. This is especially useful in the cracks of sidewalks or against houses etc. Industrially I have seen specialized machines that run through the rows of corn and killing weeds between rows. Common sense dictates that there is risk to using a torch weeder where flammable mulch is present. But as I mentioned the flame only needs to get close enough to the weeds to scorch them. It is plausible that you could use it around bark mulch if the flame doesn’t contact or overheat the bark to the point of combustion before drying out the weeds. Weed fabric should be protected by a gravel mulch. I should also point out that the torch weeder is great on annual weeds or other weeds that have not formed underground storage organs. Older perennial weeds may resprout from underground structures after they are scorched back. For example dandelion could resprout from its underground taproot after the top is scorched back.

-- HG