Xtremehorticulture

Colder than Normal Spring Weather and Tomatoes

Q. We read your early spring article in the RJ on tomatoes and planted 6 plants in mid-March.  We planted a mix of ‘Sweet 100s’, ‘Champion’ and another plum tomato.  We have been watering, using Miracle Gro for tomatoes and watching them closely.  The plants appear stunted.  We have them in cages, and they have only grown a short distance up the cage. Any suggestions? The smaller tomatoes, pear, cherry and grapes are always a sure thing in Las Vegas. The larger tomato is ‘Black from Tula’, an heirloom type. When the spring season is long and cooler, tomatoes do better. A. Planting dates for tomatoes in our climate can range from mid-February to mid-March. Watch the weather and use your weather app on your phone. It’s been cold lately. Wait for temperatures to warm up a bit. Tomatoes are a “warm season” crop, and they prefer soil and air temperatures a bit warmer than our spring provides at times. Our spring temperatures have been erratic. Low soil temperatures can slow tomato growth even if the air temperatures are high.  Its short stature gives this away as a determinate type of tomato.             About a week before you are to plant tomatoes, cover the soil with clear plastic and seal the edges. This is so the warm temperatures under the plastic don’t “leak out”. Warm the soil temperature to at least 65 F in the top few inches. I would slit the plastic and plant at that temperature. A soil thermometer stuck in the soil an inch or two deep helps you to check it. Tomatoes can be started a bit earlier if the soil is covered with plastic and there is good weather.             Raised beds in full sun warm up much faster in the spring than those raised beds in the shadow of a wall or home. Have two raised beds: one for early production in the spring and another for later production.

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Pear Tree and Fireblight Disease

Q. I  attached pictures of my pear tree. Do you have any idea why the leaves are doing this strange browning and dying out? Never seen anything like this. Both pictures were submitted by the reader. Sure looks like fireblight disease to me. A. I’m going to state the obvious. The leaves turned brown because they are dead or dying. I know you want to know why they are dead. The usual reasons can be wide-ranging and related to either diseases, damage to limbs or the trunk or soil problems. The possibility that concerns me the most is a disease called ‘fireblight’. Search the Internet or my blog for pictures of what fireblight disease looks like. Check the entire tree for this kind of damage. Advanced stage of fireblight disease. The tree can still be saved by pruning back about 12 inches to stop the disease from spreading. If you are at all suspicious of fireblight, then prune out these branches 6 to 8 inches below this area and use a sanitized pruning shears. If more than one cut is needed, then sanitize your pruning shears between each cut. Use 70% isopropyl alcohol or higher or a cigarette lighter and heat up the blades to kill any possible disease organisms that you could transfer to the cuts. Make sure the tree was planted with compost mixed into the soil as an amendment at planting time. Never surround fruit trees with rocks or gravel on the surface of the soil. Woodchips that can decompose and benefit the soil are much preferred over rocks for any kind of fruit tree. Fireblight disease on recently planted ‘Bartlett’ European pear. If you are watering daily, the tree roots could be suffocating because the soil stays wet and not draining properly. Root suffocation can also cause the leaves to die and turn brown or black. Stop daily watering. Water every other day or every third day during the heat of the summer. Apply enough water when irrigating to cover a large enough area under the tree to initially wet and keep this soil from totally drying out until the next watering. Pear trees grow very well in our climate if the soil is prepared at the time of planting with compost and if the soil surface is covered in woodchips after planting. You should never have to water daily if you are giving the trees enough water, over a large enough area, when you are watering.

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Using Pheromone Traps to Control Wormy Apples

Q. We have six apple and two pear trees in Ely, Nevada. This year all the fruit had worms in them. The damage started when the apples were only about 1 inch in diameter. Every single fruit had worms in them. I am suspecting a moth but I’m not sure. We sprayed with Neem Oil before they blossomed and after the fruit set. Any ideas? A. This “worm” is the juvenile or immature form of a moth called the codling moth. They ruin the apples or pears by devouring the inside of the fruit leaving their feces and allowing for the fruit to start rotting. Hence, “wormy apples” which can look disgusting later. In commercial apple and pear production, as many as eight “cover sprays” are applied to the trees every year to prevent wormy apples. An early sign your apples may be wormy. The codling moth lays an egg on the outside of immature apple or pear fruit. The warm hatches and tunnels inside the apple. Conventionally, insecticides are sprayed on the trees and fruit to kill the warm before it enters the fruit.             Codling moth is the most destructive insect of apples and pears in the world. We see codling moth damage to apples and pears in the Las Vegas area as well. But because we are in the Mojave Desert, this pest is not as damaging as it could be. As more homeowners plant more fruit trees however, we will see more of this pest creating damage to these fruits in the future. This is a winged sticky trap with a reddish brown rubber lure that was impregnated with a pheromone. This sex hormone is released into the air and one gender of the past is lured to the trap where it is stuck. When the sticky bottom of the trap is full or no longer sticky, it is replaced. In a dusty environment this can be weekly. The lure weakens over time and is replaced to keep the scent at its maximum filling the air.             As I mentioned in passing, one method of control is using insecticides as a “cover spray”. A cover spray is an insecticide sprayed over the entire tree, not just the fruit. Sprays are applied often enough to create a poisonous barrier for the female codling moth. Neem oil will not work in this way against this pest. This is a Delta trap used mostly for monitoring when the moth is flying. It does a great job telling you when sprays are needed. I like the trap better when relying only on disrupting the mating of insects for control.             If you choose to use an insecticide, it must be something other than Neem oil and it must be sprayed frequently over the entire tree. There are insecticides you can purchase from the store but the secret is to apply it often beginning when the fruit first begins to develop.             Another option, pheromone traps, can either reduce the number of times the tree is sprayed or even eliminate spraying altogether. Pheromone traps are cardboard traps which contain a sex hormone released into the open air. This pheromone prevents the male codling moth from finding a female and, instead, gets stuck in a sticky mess inside the trap.             Under some circumstances, these pheromone traps may catch enough males to prevent female moths from laying their eggs. This interruption in mating can prevent wormy apples from occurring.

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Blackened Dead Leaves May Be A Really Bad Disease Problem from Last Year

Q. I planted a five-gallon pear tree about three springs ago and it seems pretty happy espaliered along my west-facing block wall, but a few new leaves on three of the branches have some kind of black rot on them. It has rotted away part of the leaf on some of them. Can you tell me what this disease is and whether and how to fight it? Also, don’t know if this is for the same reason or not, but the pear did not have blossoms this spring. If it matters, it’s a Comice pear. I have a Bartlett planted nearby at the same time, and it seems unaffected. A.  Two things come to mind. First, last year was a pretty bad year for a disease that attacks European pears, Asian pears and apples. This is a bacterial disease called fireblight. What you are seeing now in spring 2014 may be a remnant of fireblight from the previous growing season (2013). It can be particularly bad on Asian pears. Again in about May you see some of the new growth dying back from fireblight, dead leaves and upon close inspection the blackened growth. New succulent growth in May in our climate causes the blackening of the growth and the telltale hook or shepards hook commonly talked about with fireblight This disease can be devastating to these fruit trees. The disease normally starts near where the flowers are produced. This disease can spread down the limbs and in the case of Asian pears in our desert climate, the disease can kill the tree. It normally does not do this to European pear or apple here in our climate. The disease turns these parts of the plant and even some small limbs dark black, like they were scorched with fire, hence the name. A telltale sign is distorted young growth in that area that is bent backwards into a hook. If this is the case or you suspect it might be then cut out this diseased portion 12 inches below the infection. Sterilize the pruning shears or saw with a strong disinfectant such as alcohol or Lysol. Do that between each cut on that particular tree to prevent reinfecting it. I pay particular attention to the weather during bloom time (that is happening now in apples and pears in our climate). If it is rainy and windy I can usually expect problems from fireblight. That is exactly what happened this time last year. The second thing is that pear leaves normally turn black if they are injured in some way. That would be a normal color for damaged or dying or dead pear leaves. So if it is just affecting the leaves and they are black then I would not assume it to be fireblight. But if it is in the branches then you need to cut out the infection as I described.

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