Plant Diseases

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Leaf Problems On European Ginger

Without culturing samples in a lab it's impossible to know which bacteria (less likely) or fungus (most likely) is causing this problem, but even without a definite diagnosis the actions for the home gardener would be the same. Know that the cool night temperatures that most of the Northeast has experienced this summer have lead to a variety of fungal/mildew problems on many plants.
1. Cut out the most damaged leaves and foliage and throw them in the garbage.
2. Be sure that you only water this area deeply once a week. Get a rain gauge and if nature hasn't delivered an inch of rain that week, water with a sprinkler in the morning until the rain gauge (not any thing else - a carton isn't the same as a real rain gauge!) shows between 3/4 and one inch of water. Then don't water again for 7 days. Never hand water, especially in the evenings. Every fungal disease in the book lists too frequent watering as one cause.
3. After removing the worst of the leaves spray with one of the organic fungicides such as Actinovate, Serenade, sulfur or copper.
4. Continue to pick off the worst of the symptoms and throw them out.

By | 2016-01-22T18:19:42-08:00 January 22nd, 2016|Plant Diseases|0 Comments
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Marginal Leaf Scorch On Pear

This could be an infectious disease (we've included a link about this at the end of this response), but its more likely marginal leaf scorch caused by high salt content in soils and/or water. If watering is done for brief periods of time, this can cause a build-up of salts at the root zone, which results in brown scroch of the leaves, usually at the edges and tips. Fertilizer that has not been watered-in very well can also cause this damage. We recommend watering for longer periods of time (but less frequently) to push the water and salts further into the soil. (We've included two links about this). If you think you're already doing this and salt burn/leaf scorch is not the cause, we recommend you check out the link about bacterial leaf scorch.
https://www.extension.purdue.edu/extmedia/bp/bp_25_w.pdf
http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/environmental/scorch.aspx

From the link: http://soilplantlab.missouri.edu/plant/diseases/scorch.aspx
"Bacterial Leaf Scorch in Landscape Trees
Cause: Xylem-limited bacterium, Xylella fastidiosa. This bacterium is transmitted by leafhoppers. The bacterium grows in the xylem of the plant and physically clogs the vessels. This in turn creates water stress."

By | 2016-01-22T02:17:02-08:00 January 22nd, 2016|Plant Diseases|0 Comments
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Black Spot On Roses Thats Not Typical

We understand why you question whether this is blackspot or something else. The confusing thing is that sometimes the blackspot fungus Diplocarpon rosae is pictured as being round dark spots, often with a lighter center. So when we see dark spots that have fuzzier edges it seems like this might be another disease. But there aren't other rose diseases that look like this.

To combat black spot early in the season, try to water so that the foliage isn't splashed. It's easier to stall this disease or prevent it than it is to treat it once the plant already has the fungus. Plant resistant varieties when possible. Spray with a fungicide labeled for blackspot right from when the plant breaks dormancy. Repeat that spray once most of the leaves have dropped off, coating the stems to kill any of the fungus that is remaining there. Rake up all fallen leaves and throw them out. Never water a rose in the evening or night, only in the AM so that the foliage dries quickly. Mulch early in the season to cover up any fungal spores in the soil and prevent them from splashing onto the foliage.

You can see blackspot photos that look more like your plant here: http://www.hgtvgardens.com/garden-basics/preventing-rose-diseases
and here: http://www.backyardnature.net/n/x/blakspot.htm

By | 2016-01-20T18:37:13-08:00 January 20th, 2016|Plant Diseases|0 Comments
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Septoria Leaf Spot

This is Septoria leaf spot. If flourishes in damp or humid air and frequently splashing the foliage with water will encourage this fungus to get established. We see it in many gardens this year, mostly on peppers and tomatoes. First, remove all the affected leaves and place in the trash not the compost pile. Next year rotate your tomatoes because the fungus will over winter in the garden for a season and would affect next years crop. This is specific to tomatoes not cucumber or the like. Good air circulation is very important when planting. Sterilize all your garden equipment that comes in contact with the tomatoes so it doesn't spread. Mulch your tomatoes if you haven't already. It keeps the spores from splashing on the ground and spreading the disease. If the above measures do not control the disease, you may want to use fungicidal sprays. Fungicides will not cure infected leaves, but they will protect new leaves from becoming infected. Go to your local garden center for recommendations about an organic fungicide that's labeled for septoria leaf spot. Apply at 7 to 10 day intervals throughout the season according to directions. Follow harvest restrictions listed on the pesticide label. When spraying the plants, make sure you spray the undersides of the leaf as well.

By | 2017-09-11T15:49:26-07:00 January 20th, 2016|Plant Diseases|0 Comments
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Powdery Mildew On Hydrangea

Sorry for the delay in responding! Hard to say definitively without more info, but looks like at least part of the problem is Powdery Mildew (the white powdery mildew spots). The green mottling (among the yellow tissue) could be the symptoms of another fungal disease called Rust, so we suggest you look at the bottom of the leaves (it is usually orange/rust in color). The spotting of the upper surface of the leaf could be a result of that, or it could be a combo of things. See the links included for more info on Powdery Mildew and Rust. We also recommend that you provide air circulation in/around the plant as much as possible, and keep water of off leaves as many fungal diseases spread with water. We also recommend proper water and fertilizer applications. Excesses of either one (or insufficiencies of either one) can reduce plant health and cause them to be more susceptible to pests and disease. The links we've provided will also give you info about those cultural practices. You should also remove any infected leaves (without defoliating the plant) and in the case of Rust, consider asking your local garden center for a fungicidal recommendation.
http://www.ipm.ucdavis.edu/QT/powderymildewcard.html
http://www.usna.usda.gov/Gardens/faqs/hydrangeafaq2.html (look for Rust at this link)

By | 2016-01-19T07:35:04-08:00 January 19th, 2016|Plant Diseases|0 Comments
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Powdery Mildew On Zucchini

It is probably powdery mildew. This fungus is common to squashes (and cucumbers, which are in the same family), especially if the foliage is wet at night. Drier weather will help, but if many leaves are affected, fungicide sprays will arrest its progress and allow you to harvest.
Trim off the damaged leaves. There are several organic fungicides that are labeled for powdery mildew including Actinovate, Serenade, sulfur, and Green Cure, or ask at your local garden center. Be sure to spray under the leaves and the stems as well.

The warm days and cool nights of late summer create an ideal climate for spore growth and dispersal.

Powdery mildew can be prevented, and it can be controlled once it appears, but it can't be cured. The key to preventing it is planting mildew-resistant or mildew- tolerant varieties. Resistant varieties get less mildew than susceptible varieties; tolerant varieties may get some mildew, but it shouldn't affect the performance of the plant. Prevention also includes siting plants where they will have good air circulation, and exposing as much leaf surface as possible to direct sunlight, which inhibits spore germination.


By | 2017-09-11T15:49:26-07:00 January 19th, 2016|Plant Diseases|0 Comments
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Weak Aloe

Maine is a tough place to grow an aloe to start! It is difficult to say what's at the bottom of its declining condition but here's some recommendations. I know its a very short season by you but take advantage of what you can. As long as your night temps stay above 45 degrees, move it outside into full sun. The leaves (when healthy) should be standing somewhat up, not flopping down. The center is also very pale and weak looking. These are all signs of not enough sun and maybe too much water while it was inside for the winter. Just to be on the safe side, cut off that leaf that is turning black - it could be a fungal or bacterial infection. Use a sharp knife and cut it off right next to the trunk and toss it. Sprinkle a good amount of ground cinnamon on the cut of the main plant. It is a natural anti-fungal, anti-bacterial. When you water, water well, but don't water again until the soil has become dry to at least an inch or so into the pot. They need to dry out between watering. Just maybe it will start to perk up before you need to bring it back inside before your first frost.

By | 2016-01-17T16:50:20-08:00 January 17th, 2016|Plant Diseases|2 Comments
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Cherry Leaf Spot

Your tree may have cherry leaf spot, caused by the fungus Blumeriella jaapii. Cherry leaf spot targets the foliage of cherry trees but can also infect stems and fruit. Small purple spots on the tops of leaves are generally the first symptom of this fungal disease. The spots turn brown and begin to enlarge and collapse, leaving a hole in the foliage. Older leaves will yellow and drop from the branches, and the cherry tree can lose all its leaves, which weakens the fruit tree and increases its susceptibility to cold damage. Be sure to clean up all of the fallen leaves and dispose of in your garbage.

Properly timed applications of fungicide will help prevent cherry leaf spot. Start fungicide preventive sprays at the petal fall stage and repeat every seven days until harvest. Some say way until the new leaves in the spring and others to start treatment now. It would be best to confirm that this is the problem and go from there. This happens a lot in humid weather places with often with overhead watering.

You may want to get a second opinion and take a sample to your local cooperative extension for confirmation. They will also be your best source for treatment of the problem.

By | 2016-01-17T15:10:50-08:00 January 17th, 2016|Plant Diseases|0 Comments
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Powdery Mildew On Tomato Foliage

This looks like powdery mildew, a common fungal disease that crops up where air circulation is limited and nights are cool and humid. Growing in shade also makes the problem worse. Spray the plants with any of the organic fungicides such as Actinovate, Green Cure or Serenade. Your local nursery may have other options. Fungus disease cannot be cured, but can be arrested so plants can continue to grow and produce. Keep the affected leaves picked off the plant and up off the ground to prevent reinfection. There are various types of Powdery mildews and many of them are host specific (Powdery mildew of tomato won't spread to roses, for example), so you may have more than one type of mildew. You will likely need to make changes to the overall environment to reduce the spread, like increase air circulation in/around the plants with pruning of some stems and leaves, make sure air movement into the garden area is sufficient (not being blocked by other plants or structures), and the plants requiring full sun should BE in full sun all day (at least 6-8 hours/day).
Here's more info about Tomatoes and Powdery Mildew:
http://www.ipm.ucdavis.edu/PMG/GARDEN/VEGES/tomato.html

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7406.html

By | 2016-01-17T01:51:30-08:00 January 17th, 2016|Plant Diseases|0 Comments
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Powdery Mildew

This appears to be a strong case of powdery mildew. We recommend organic treatment whenever possible. Serenade is an excellent organic fungicide. Powdery mildew is unattractive and it can affect the flavor and reduce yields of some fruits and vegetables. Although plants are unsightly and can be weakened by an infection, they do not usually die. Powdery mildew on ornamentals is an aesthetic issue, and not usually worth treating. Prevention and control is more important for vegetables. Powdery mildew can be prevented, and it can be controlled once it appears, but it can't be cured. The key to preventing it is planting mildew-resistant or mildew- tolerant varieties. Resistant varieties get less mildew than susceptible varieties; tolerant varieties may get some mildew, but it shouldn't affect the performance of the plant. Prevention also includes siting plants where they will have good air circulation, and exposing as much leaf surface as possible to direct sunlight, which inhibits spore germination.To control minor infestations, pick off affected plant parts and bag them tightly and put them in the trash. Utilize an organic fungal control like Actinovate or Serenade.

By | 2017-09-11T15:49:27-07:00 January 16th, 2016|Plant Diseases|0 Comments
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