Extension Educator, Local Food Systems and Small Farms
Extension Educator, Horticulture
May 21, 2013
May 21, 2013
What a difference a year makes! Last year we were warm and dry for large parts of the spring, and this year has been cool and damp for the most part. With the type of weather we have experienced, it should have been expected many different diseases would come our way this spring. Well, they are here. Here are some shorts on the past week and some of the items found without looking too hard.
Peach leaf curl is caused by a fungus on trees in the stone fruit family. This would include mainly peaches and plums. It is rather striking with the bright red swellings on the green leaves. This disease can only be prevented with a dormant time application of a fungicide on your trees. Seeing it now means that you probably should have sprayed before the buds began to swell (meaning before leaves actually came out).
Anthracnose starts as dead leaf areas between leaf veins, or on the tips of leaves. When severe enough, leaves will fall. Several of the infected trees have actually had the leaves turn completely black already. It is much more noticeable on one side of many trees as well, due to air movement carrying the disease and drying out foliage quickly. The good news is that it rarely harms trees. If enough leaves drop, a new set comes out in 4-6 weeks and we start all over. The next set of leaves may also get the disease, but they may not. Infection can continue with weather favorable to the disease, and when nighttime temperatures stay under 65 degrees. Treatments when you see the symptoms of this disease are simply wasted time and money.
Apple scab is a disease similar to anthracnose, and can cause premature leaf drop in apples and crabapples. If you are on a regular spray schedule for fruit trees, it should prevent most of the problems. You could also spray crabapples this way, but you would have to weigh the cost and benefit since no fruit production is involved.
As a reminder, spray programs for disease prevention in fruit trees should be applied every 10-14 days after the bloom period is over. It should be stressed that these are preventative programs, and not curative. These programs then continue until roughly two weeks before the fruit is ready to harvest.
May 21, 2013
Many major tree diseases cause vascular system blockage. Verticillium wilt, oak wilt, and most of the canker diseases fall into the group. Usually a fungus "plugs the pipes" so there is reduced movement of water up and food down. This leads to dead areas above the blockage. Of course, if the blockage is on the main trunk you end up with a dead tree. It is often possible to see streaking of the wood, or a dark ring around the center portion of the branch or trunk with verticillium wilt, but a lab analysis is needed for definite confirmation. There are no cures for any of these diseases at this time. It is recommended to remove and destroy trees severely infected with verticillium, to help prevent transfer from root grafting. The list of trees affected by verticillium is very large, but good quality maples are very susceptible. There have been many affected trees this year, including maples and ashes. The only treatment is to water and fertilize to try and get new growth, and new water and food carrying tissues.
We have really had twenty-plus years of stressful weather. Just like us, trees like moderate weather. When we have extreme heat and cold, and no moisture or a flood, the trees are stressed. This stress makes them more susceptible to things that are always in the environment. Try to even out some of the extremes by watering when it is dry, fertilizing when you do the lawn (or just fertilize the tree), and mulching to even out the soil temperature in the root area. Remember that many diseases can be passed with pruning equipment, so disinfect your equipment between cuts.
May 14, 2013
Many pumpkins are being planted about this time. While this practice is great for producing pumpkins for pumpkin pie, it really doesn't work very well for producing the Halloween jack-o-lantern pumpkins. The Halloween pumpkins are best planted around Father's Day. This timing helps prevent the pumpkins from rotting before we get to the end of October.
Many different varieties are available, and they come in many sizes and shapes. The small pumpkins, ranging from two to five pounds, are called "pie" types. They are normally used for cooking and fall decorations, and include the Baby Bear variety. Intermediate and large varieties are primarily used for jack-o-lanterns. Many of the newer varieties have stronger side walls to aid in display and carving. The flesh of these varieties is generally poor in quality and not used for cooking. Processing pumpkins, that are canned commercially make poor carving pumpkins, and are more like a buff colored watermelon in appearance. The jumbo or mammoth varieties are mainly used for exhibition. These jumbos can weigh in the 900 pound range. For most homeowners, you might want to pass on these since moving a 900 pound pumpkin isn't for everyone. The other option is to try and grow one in place.
Vining pumpkins need at least 50 – 100 feet per hill, with the larger pumpkins requiring the larger area. Hills should be five to six feet apart and rows of hills should be 10 – 15 feet apart. Each hill should have about four seeds per hill, planted about an inch deep. The miniature varieties such as the Jack-Be-Little are sometimes grown in rows with seeds planted every eight to twelve inches, then thinned to about two feet apart in the rows. Fall decoration pumpkins should be cut from the vine before the vine dries in order to have a good stem attached to the pumpkin, but after the color is acceptable.
Keep the pumpkin bed free from weeds by shallow hoeing, and make sure it is watered during extended dry periods. Major pests are squash bugs, cucumber beetles, and vine borers. Most often, frequent applications of an insecticide such as carbaryl will help protect the new runners from the vine borers and also control the beetles that transmit the wilt virus. Make sure no applications are made to open blooms that attract the bees for pollination, by applying insecticides in late afternoon or early evening.
May 7, 2013
It's that time of year for those who have rhubarb to start enjoying the fruits of their labors. Rhubarb is actually considered a vegetable, even though it is used as a fruit in pies, sauces, tarts, and even in wine. This hardy vegetable can usually remain in one place for five years, and sometimes even longer.
There are two basic types of rhubarb. There are red petiole varieties and green petiole varieties. Petioles are the leafstalks of the rhubarb plant, and those are the edible portions. The leaves of rhubarb contain large amounts of oxalic acid and are toxic. The leaves should also not be fed to livestock or pets. Many people ask about the poisonous properties of rhubarb after a frost, and there is a potential for the oxalic acid to move from leaves to the leaf stalks after damage is done to the leaves. It usually takes a freezing temperature of about 28 degrees to cause this amount of damage, and you can see the damage on the leaves when it shows up as water-soaked tissue that turns brown or black when it dries out.
Rhubarb is best divided in early spring before it breaks the ground. We're about a month late for the division process this year. Each crown area can be cut into four to eight pieces and re-planted. You just need to make sure you have at least one good bud per section. The first year of establishment, you shouldn't harvest at all. The second year you can have one or two weeks of harvest. After the second year, you can harvest of eight to ten weeks. Pull the stalks, and don't remove more than a third at any one time.
The appearance of seedstalks is a common problem. This tends to happen with cheaper plants grown from seed, overcrowding, plants that have begun declining and need to be divided and re-planted, or plants suffering from low fertility. When seedstalks do appear, simply cut them off at the base of the plant. The production of seedstalks tends to make the leaves and petioles smaller.
May 7, 2013
Everyone seems to have been waiting for warmer temperatures, and the appointed date, to begin broadleaf weed control programs. Well that time will come, believe it or not. We have also been waiting for a period of drier conditions with lighter winds. For most of the broadleaf products to work, the temperature has to be over 55 degrees. These chemicals do work better when it is warmer and the weeds are actively growing.
The first item of business is to know what type of weeds you want to control. This will make a big difference in what product, or products, you select. One website useful in identification and control of weeds is http://www.turf.uiuc.edu/weed_web/index.htm . It gives a variety of pictures, as well as control products. Of course, you get to click on a weed by name to see the pictures. You may have to click a bit to find the one you are after. Always read the label for weeds controlled, potential drift, and other safety recommendations.
The main products used for broadleaf weed control in lawns are 2,4-D, MCPP (mecoprop), dicamba, a combination of those three products, and triclopyr alone or in combination. Let's start with the triclopyr since it's probably the easiest to discuss. Its place in weed control is for hard to control weeds and woody plants. It also improves control of violets. It can be added to one, or more, other chemicals to provide broad spectrum control. Some blends now contain trichlopyr, so check the label under active ingredients.
2,4-D is the old standby. It is good on carpetweed, chicory, dandelion, lambsquarters, plantains, and wild carrot. MCPP is good on chicory, lambsquarters, and white clover. Dicamba is good on black medic, chickweeds, chicory, dandelion, dock, henbit, knotweed, lambsquarters, pearlwort, purslane, red sorrel, thistles, white clover, wild carrot, and yarrow. The combination of all three products will pick up all of those listed for the individual products, plus a few more such as mallow, speedwell, and wild onion. The combinations are sold under many different trade names, so check the active ingredient list for ones you need.
May 2, 2013
May 2, 2013
One group of problems showing up is galls. Galls are swelling of leaves, twigs, or other plant parts. Most are caused by mites or wasps. They damage the plant parts and the plant responds with a gall. In the case of leaves, the swelling is actually leaf tissue. This is something I like to refer to as similar to you getting a mosquito bite. The damage comes in and a swelling occurs. There is no way to get rid of it without tearing a small hole in the leaf. The maple leaf bladder gall will be easily spotted on silver maples in the area shortly, as will oak leaves in the red oak group. Probably the shingle oak has taken the honors for most galls this year.
Oak trees probably have more galls than any other group of trees. Several samples have also been brought in of the stem types of galls. Fortunately, the oak galls are usually not the type to kill tissue beyond them. However, the galls aren't the most pleasant things to look at. That is the main thing – they are unsightly. There is no cure for galls, as they are caused by insects before you see the swellings. The timing would be impossible to try and prevent the insects.
May 2, 2013
With alternating warm and cool (or cold) weather, we see many nuisance pests when we get the warm days. We've been through the second round at least, and I'll guarantee at least one more round this spring. Add to that the fact we are more active on the warm days, and we are doing things like destroying their resting places by cleaning off flower beds and raking up piles of leaves.
Asian ladybugs, millipedes, boxelder bugs, ants, and termites are just some of the things that can "bug" you. The only one in the short list that can do real damage is the termite. If you have a termite problem, it is recommended to consult a professional to handle the matter for you. For the other pests, a nuisance is what they are. If you've already removed the resting places such as leaf piles, firewood stacks, and similar places, we are probably ready for the foundation spray. Foundation sprays of permethrin or bifenthrin are the standbys. Simply spray the foundation of the house and the adjacent foot of soil. In severe cases, you may need to expand the soil treatment area. The larger the barrier, the more effective it is.
I mentioned ants and termites earlier. Swarming time for both insects is about the same time, and they are really looking to start new colonies because they have outgrown their old ones. This is the reason for the winged insects. The wings allow the ants or termites to cover larger areas to start their new colonies. The differences between ants and termites are several.
Termites are always blackish in color, while ants may be black or other colors. If you have winged insects that are not black, you don't have termites. Next, look at the body shape. Ants have a constricted "waist" while termites don't have that classic hour-glass figure. Antennae and wings are the other two body parts to look at. Antennae on ants are elbowed, basically in an "L" shape, and those on termites are straight. Both ants and termites have pairs of wings, but termite wings on the same side will be of equal length, while ant wings are of different lengths on the same side.
Ants can be controlled on the outside of the house with the foundation treatment mentioned. Inside the house, bait stations that don't immediately kill the ants (allowing them to take the bait back to the colony) are effective. However, you have to wait about a week before you do anything else. Inside the house, it is only recommended to use aerosol cans or pre-mixed spray bottles labeled for indoor use. If you use the bait stations, wait the week before any spraying.
April 23, 2013