A Few Abiotic Problems on Tomato

Thanks to "Mother Nature" in 2012, many gardeners and commercial growers have been battling abiotic problems of tomatoes!  Many have been taking notes and comparing problems on tomato cultivars that are more susceptible to abiotic conditions on fruit such as Yellow Shoulder, Sunscald, Rain Check, and Fruit Cracks.  Other abiotic problems on tomato fruit are Blossom end rot, Catface, Spider Track, Puffiness, and Internal White Tissue.

The pictures below have symptoms that are suspected to be Rain Check.  

Rain check is the many, tiny concentric cracks that form on the shoulder of the fruit.  Damage will be most visible on the exposed, mature green, and possibly breaker fruit after rains; but unexposed fruit or small, immature green fruit sometimes be affected as well.  This problem is mostly observed on large, fresh-market tomatoes, rather than on smaller fruited cultivars. If conditions are right, black shoulder can occur (as seen in the pictures below.)

The cause of rain check is not known.  The rain might alter the fruit temperature or water uptake.  This, in turn, may hinder the development of the shoulder epidermis.  Another theory is that the rain could promote this problem.  This abiotic disease is often worse when dry periods are followed by heavy rains.  

Cultivars can vary in their susceptibility to rain check.  Those tomato cultivars that have good leaf cover to protect tomatoes and good epidermis characteristics seem to be more tolerant of rain check.  Glossy fruit tends to have less rain check than dull fruit.  

Management:  Choose tolerant cultivars and cultural practices that reduce fruit exposure.   

 

Another abiotic problem on tomato fruit (as seen below) is called zippering, which is a thin, brown, necrotic scar, starting at the stem and can extend partly or all the way to blossom end.  This long scar has transverse scars across it, which resembles a zipper.  Often times, there is only one zipper that forms per fruit, but there could be several zippers.  

The cause of zippering is anthers that attach to the ovary wall of the newly forming fruit and seems to be more pronounced in cool weather, but can occur during other weather conditions.  Tomato cultivars will vary in their susceptibility.

Management:  Grow tolerant cultivars and maintain proper temperatures when growing in a greenhouse.  

In conclusion, how can you try to avoid most of the abiotic diseases of tomato fruit:

• Fight with Mother Nature
• Provide even watering (if possible)
• Provide even temperatures (greenhouse)
• More nitrogen or overfertilization can be bad!
• Don't get too crazy with your pruning!
• Control disease and insects
• Overall, maintain good nutrition of tomatoes
• If you continue to have a problem, you may want to consider growing a different tomato cultivar

Bacterial Culturing at the U of I Plant Clinic

(Blog written by U of I Plant Clinic Student, Sean Mullahy)

When dealing with a plant sample, the first step is generally to determine the causal agent of the problem: abiotic factor, fungi, bacteria, or a virus. Once this is determined, each agent has a different method of approach. Today we will be dealing with a bacterial pathogen, so the first step is going to be the search for the illustrious bacterial ooze. Plant pathogenic bacteria have an interesting property in that they will “ooze” out of tissue when sliced. With a large enough (and well infected) sample, this can actually be seen in a beaker or glass of water. With a smaller sample, a small section of infected tissue is sliced, preferably at a transition zone, and then mounted onto a slide. Under the scope, along the edges of the cut tissue, bacteria can be seen streaming out in what can be best described as a mist or a cloud. Once this is found, we can move onto the next step, the best step, the culturing step.

 Bacterial ooze!

The transition zones mentioned previously are next going to be used to make up our nasty and kind of creamy bacterial broth. These zones are selected, cut, and then surface sterilized with a quick dip in a 10% bleach solution. Following this is a quick dip in distilled water, they are then left to dry in the crease of a paper towel in our flow hood. Once air dried the sample material is placed in a test tube of sterile water, shaken up, and left to sit for at least 30 minutes. This is when the bacteria start streaming out into the water, making what can be best described as a “broth” of bacteria. This nasty little tube of liquid is what will be used to culture out our bacteria.

 In this case, we suspect a Pseudomonas bacteria, so we have chosen Kings B or Pseudomonas Agar. This medium is pretty cool in that most bacteria will grow just fine on it, but if a Pseudomonas bacteria is cultured on it. This agar will glow under UV or blacklight, once there has been adequate bacterial growth. The Plant Clinic cultures its bacteria in two ways, either by spread plates or streak plates. Both techniques are quite easy, with each having its own benefits. In one technique, an inoculating loop (a small wire loop) is used to grab a droplet of bacteria solution which is then “streaked” over the agar plate.  The other technique is called a spread plate. In this a larger amount of the liquid bacteria solution, 1/10 of a mL, is pipetted onto the plate. A bent glass rod is then used to “spread” it evenly over the surface of the media. 

Hopefully you found this quick look behind the scenes at the U of I Plant Clinic to be informative (and hopefully somewhat interesting too).

Todd Gleason's Sunday Drive to Determine Illinois #Corn Yields

On Sunday, a member posted the following on a private agronomic Facebook page:

"Do you follow Todd Gleason (University of Illinois Farm Broadcaster) on Twitter? @commodityweek. He just did a big loop today from C-U to Jacksonville and south and back east through Litchfield to Dalton City. They were driving 20 miles, stopping at first corn field @ first culvert and walking in 50 paces and pulling 3 ears in so many steps."

After seeing this post on Facebook, I quickly checked out Todd's posts on Twitter.  If you are interested in corn yields around the state of Illinois, I suggest that you check it out too!

Thanks to the magical world of social media, Todd saw that I was following his "Sunday corn yield journey" and sent me an email with further information and pictures. 

Above is the route and actual field stops.

The above photo is taken near Pana, Illinois, my home county, and can give us some hope that some areas in Illinois may actually have some fair yields.  My Dad farms not too far away from this location, but I don't know that our corn looks this good.  The rains were "hit and miss" and very spotty this year in our area.

Above are Todd's photos of corn ears from each field visit from left to right.  He got an actual "0" in Carlinville, Illinois.  

Why did my maple die so suddenly?

Every day I receive calls about plant problems.  It is often very, difficult for me to determine what the problem may be over the phone.  So, I ask for plant samples or pictures, depending on the description of the problem.

In this case, this maple died very suddenly.  This does not sound like a disease or insect problem to me.  Yes, maples can have problems with Verticillium wilt, but let's not be too quick to blame this disease.  Further investigation should be done.   First of all, the drought and heat this summer have been very, harsh on tree health.  Unfortunately, if that tree has any preexisting decline problems, this stressful weather will not help! 

I usually ask for a picture of the tree base.  Here I can see that this tree is suspect for being planted to deeply.  It is hard for someone to believe, but yes, a tree can survive for many years being planted to deeply; however, when harsh growing or site conditions arrive, the tree can quickly decline.  It is also possible that this tree could have had a girdling root on it's left side.  Deep planting and girdling roots can cause the tree to decline.  But, could the hot/dry weather and incorrect planting cause the tree to die suddenly?

If a root rot or wood decay fungus infects the declining tree.....yes, that can cause a sudden death. The symptoms of the maple in the above pictures are very symptomatic of Armillaria root rot. For more info, you can check out this link: http://www.na.fs.fed.us/spfo/pubs/fidls/armillaria/armillaria.htm

There are some species of this fungi that are just saprophytic (survive on dead wood), but there are some that can be parasitic (cause disease). I can’t tell you which came first. It is still possible that that the girdling root/deep planting killed the plant and then Armillaria invaded later. But, Armillaria root rot could have caused the tree to die too.

Waterhemp Herbicide Resistance Testing in Illinois

The U of I Plant Clinic has receive many questions in the last week about testing waterhemp for herbicide resistance.  The U of I Plant Clinic is not the lab that is performing this testing, but here is the information needed below.

In case you are not sure what a waterhemp looks like, here are some pictures:

With continued support from the Illinois Soybean Association, U of I can offer free screening of waterhemp populations for herbicide resistance again this growing season.
To submit samples, follow these directions:

• After applying glyphosate, select five waterhemp survivors in the field.
• Remove the top inch or two from each plant (containing young, newly emerged, healthy leaves), and seal it in a sandwich-sized zip-top plastic bag. Use a separate bag for each plant.
• Place the bags in an envelope and send by overnight delivery to Dr. Chance Riggins, 320 ERML, 1201 W. Gregory Dr., Urbana, IL 61801. Ideally, samples should be sent the same day they are collected, but if necessary, they can be stored for a day or two in a refrigerator (but do not freeze). Do not send samples on a Friday or Saturday.
• Print the following submission form (Adobe PDF) and complete a copy for every field sampled.

Not every waterhemp plant that survives an application of glyphosate is resistant to it. If the following conditions all apply, however, you might suspect that a waterhemp population is indeed glyphosate resistant:

• The appropriate rate of glyphosate (plus proper adjuvants) was applied at the appropriate weed growth stage.
• Environmental conditions during and after application were conducive for good glyphosate activity.
• Plants that survived the glyphosate application are found next to plants that did not.
• The field has a history of glyphosate use.

They will not charge for the screening, but please understand that they cannot promise how soon results will be available. Also, because of the way they conduct the resistance tests, a result of "sensitive" does not rule out the possibility that the plant actually is resistant, but by a mechanism different from what we are testing for. Finally, be assured that they respect the privacy of those sending samples: they will not make the exact location of any sample or name associated with them available to anyone without your permission. If you have any questions, feel free to contact Pat Tranel (217-333-1531, tranel@illinois.edu)--Pat Tranel and Aaron Hager

Authors:
Pat Tranel
Aaron Hager

A Sharp Dressed Pest - Cucumber Beetles

(By U of I Plant Clinic Student Worker, Sean Mullahy)

These infamous garden pests come in two patterns, spotted and striped, and are fantastic at destroying all things cucurbit. So beware their interesting fashion sensibilities, and protect your garden against these nasty little pests. 

The first step to keeping them under control is proper identification. The spotted beetle is about ¼ inch in length and has yellowish green forewings with twelve distinct black spots. The striped cucumber beetles are nearly the same in size, also averaging about ¼ inch in length. These have much simpler fashion sensibilities, with two distinct black stripes running down each of their wing covers. The innermost stripe on each matches up with the one on its partner wing, making it appear as though they only have three black stripes. It can also be easy to confuse the striped cucumber beetle with the western corn rootworm. They have similar color and patterns, but the western corn rootworm has a yellow abdomen, and the striped cucumber beetle has a black abdomen. The larvae for both are striped, but spotted cucumber beetle larvae are whitish – yellow in color. Cucumber beetle larvae are much bigger than their adult stage, ranging from ½ to ¾ inches in length, and they have dark brown heads and three pairs of very short legs. 

Adult southern corn rootworm (a.k.a. spotted cucumber beetle), Diabrotica undecimpunctata howardi (R.L. Croissant, Bugwood.org).

Striped cucumber beetle (Whitney Cranshaw, Colorado State University, Bugwood.org)

Striped cucumber beetle (David Cappaert, Michigan State University, Bugwood.org)

Western corn rootworm beetle (Whitney Cranshaw, Colorado State University, Bugwood.org)

As for life cycle, both spotted and striped cucumber beetles overwinter as adults. The striped beetle is the only one that will be a big issue in early spring however, the spotted beetle has a much lower success rate in surviving the Illinois winter. It, however, can be a bigger problem in southern Illinois. Once active, they begin feeding, and can survive off the pollen and petals of many different plant species before cucurbits are planted or growing. Once the cucurbits are actively growing, they move onto these, with the ability to feed on foliage and fruits and truly devastating anything they can munch. These adults eventually lay eggs at the base of their hosts, and once hatched, the larvae will feed on the roots. Depending on location, this cycle can be repeated up to two times per season, with this only happening in warmer locales. 

If the direct damage to your tasty melons, butternuts, cucumbers, and all your other favorite hard shelled veggies wasn’t enough, the cucumber beetle also spreads a number of nasty pathogens. Throughout localized plantings, they will spread squash mosaic virus, which can be quite nasty to the fruits. They can also spread bacterial wilt of cucurbits, which affects most of your favorite fruit bearing cucurbits. 

Management of the Cucumber Beetle can be done preemptively with the application of a systemic insecticide to the soil at the time of planting. This however might be a bit much for the homegrowers out there. The only other option available is to spray a foliar insecticide when adult beetles show up.  Applications are recommended based on total adult beetle count, and if it exceeds one per ten plants at the seedling stage, or one per plant at flowering.  If you’d like to practice non-chemical control of this pest, the easiest thing to do is dress your plants in a mesh cloth to keep the pests out. The earlier the better for this method, and make sure the mesh is open enough to let in ample sunlight, while also being tight enough to keep the pests out.

Further Reading:

http://urbanext.illinois.edu/bugreview/cucumberbeetle.cfm

http://pubs.ext.vt.edu/2808/2808-1009/2808-1009.html

Sick African Violet Plant Sample

The African violet foliage showed a number of symptoms, with the majority of the sample showing mild leaf curling, bleaching, or yellowing of tissue, brittle leaves, and these symptoms seemed to affect the younger leaves more than the mature ones. It was noted that the plants were still flowering, although not as much as they had before the symptoms began appearing. What could be the problem?

Cyclamen mites can be a problem on African violet.  They can cause young leaves to be thick, hairy, deformed, brownish-green, and the cup downward.  They can be difficult to control because they can be down in the crown of the plant.  They can only be seen with a dissecting scope.  The mites must be alive and present when treated.  They can be treated with insecticidal soap or a miticide.  Read and follow label instructions.  Heavily infected plants should be destroyed to protect uninfested plants.

African Violets cannot handle temperatures below 65F at night and 70-72F during the daytime. When exposed to cold temperatures leaves can become discolored, brittle, and curl under. All of which were observed symptoms.

Too much light could also be an issue. Excessive light can lead to stunted plants with crinkled and discolored leaves.

African violets prefer a soil in the range of 6.0-6.5, and soil should be adjusted for accordingly.  A soil pH imbalance could lead to nutrient deficiency in the plant. For future adjustments, it is recommended to use something more stable such as lime or calcium, and to test the soil with a soil pH test kit.

Excess watering can also cause leaves to curl.

In addition we used the resources: How to Grow African Violets by Harrison, Heimann and Pellitteri, African Violet Care by Lerner and Dana, Growing African Violets by Cindy Haynes, and Growing African Violets by Charles Fischer (all found on the web).