Tomato plant leaf spots? New

[MuskyTrap]

After the previous thread asking about plant color, I've started paying a lot closer attention. Today I saw these spots. Didn't really look like a blight to me but.... I've never seen that in person.

Thoughts?

[jentz]

Just to wet and I would say its blight,Trim the lower branches so splash doesn't hit them,And may be start to spray with Daconal??Daconil.Google it.It will help but nothing will stop it now.Should have trimmed all the lower branches off as the plant grew.

[eurolarva]

Build a carpet of brown grass clippings around the plants. This will help prevent splashing and also help control a lot of weeds. Splashing dirt will make it easier for your plants to get blight

[Nainoa]

Ah my old Nemesis the dreaded "Early Blight."

The bad news is, you're already too late... In these conditions it shouldn't have come in as a spore, so that means it's already living in your soil and all your tomatoes are infected.

The only sliver of good news, you can start treat NOW... Like seriously, every day matters now.

Step 1: Stop off at the store and buy some organic Copper Sulfate and a garden sprayer (The kind you pump up and mist) Read directions... APPLY TONIGHT (After pinching off effected leaves and BURNING THEM.

Step 2: Continue to follow the instructions on the container for the rest of the growing season. Your plants will never be blight free, they will just not rot away to nothingness as fast etc...

Step 3: This fall have your leaf fire over that area.

Step 4: Till

Step 5: Have a second leaf fire over that area.

Step 6: Next spring do not plant any member of the Solanum family there. No Tomato, Potato, Eggplants or Peppers... Actually don't plan on planting any Solanum anywhere near that area for 2 years is your best bet, and do the fall double burn each time.

Try something like Onions/Beets/Carrots or a corn

[MuskyTrap]

Does blight usually take its toll on peppers as well? I have 6 pepper plants right next to these that show no signs of any issues.

Any chance that these spots could be just a sign or cold stress? Our weather has been horrible until the last few days.

[Nainoa]

No... Cold stress at this point would be flowers dropping (The first sign) Then spindly stems... And then you'd get a yellowing of the leaves in between green veins... This is also a sign of a magnesium deficit... Because under 39 degrees the properties of water change slightly, in a way that reduces the plants ability to transfer up key minerals from the roots

What you have is Early Blight... I've fought it many times before over the years... Thought I escaped it when I moved up here to the new ponderosa, but then found that the previous owners also had it.

I opened up a whole new 3000 square foot bed expansion and had soil trucked in to put ontop in a 2 inch layer just to do my best to keep it from crossing over.

In general, from what I've seen the blight CAN get all members of the Solanum family... And raspberries can be carriers.

While it's not "Common" for it to transfer over to peppers, what I've seen is that it's not "Rare" either... More like "Uncommon" Especially if you're going with store bought Hybrid peppers, which are generally bred to have a modest to strong resistance to the blight. (But inferior flavor)

Heirloom peppers like I grow are more succeptible... I would say in a year where I have an early blight event on the tomatoes... I'll see blight in 3 or 4 out of every 20 peppers.

It generally avoids the tropicals, like Habanero or Aji Dulce... While perferring the cooler soil temp peppers like pepproncini.

What more likely happens is that spore gets on the under side of the pepper leaves and sits there. So if at the end of the season, you don't remove the pepper plants from the garden (Like you should the tomato plants) Then it uses it as a vehicle to get back into the soil.

If you're seeing it on the tomatoes, you'll have to also watch any potatoes.

I gave everything a treatment of Copper Sulfide last night just for good measure!

[delcecchi]

Some additional info from extension

http://www.extension.umn.edu/projects/yardandgarden/ygbriefs/p256earlyblight-pot-tom.html

and

Quote:

Keeping Tomato Leaf Spots in Check

Michelle Grabowski, Regional Extension Educator-Horticulture

Early Blight infections showing rings inside of leaf spots

Trellis tomatoes to keep leaves off the ground and increas air movement around plants.

Early Blight infections just starting on the lower leaves of a tomato plant.

Photos:

Michelle Grabowski

In Minnesota three common fungal diseases plague garden tomatoes. Early Blight, caused by the fungus Alternaria solani attacks leaves, fruit, and stems of tomato plants. This disease typically starts in the lower leaves as dark brown or black spots with dark rings in the center that make it look like a target. These spots start out small but can grow to be ½ inch in diameter. Spots can grow together to cover the leaf causing it to dry up and fall off the plant. Stem infection and fruit infections are also black often with dark growth rings inside. Fruit spots typically start where the stem connects to the fruit and can grow to cover the top half of the fruit. Early Blight has been shown to be more severe in drought stressed plants, so be sure to regularly water tomatoes during this dry spell.

Septoria leaf spot, caused by the fungus Septoria lycopersici, causes only leaf spots. Septoria leaf spots are small, 1/16th - 1/8th of an inch in diameter. They have a dark edge and tan centers. Small black dots can often be seen in the center of the leaf spot. Leaves with many spots fall off the plant. In the right weather conditions, a tomato can lose the majority of its leaves from this disease, resulting in poor quality sunburned tomatoes.

Anthracnose, caused by the fungus Colletotrichum coccodes, primarily causes spots on ripening fruit. Fruit spots from Anthracnose are sunken water soaked spots often with a dark black center that will ooze pink spores in wet weather. This fungus rots the fruit from the inside and often makes it inedible. All three of these diseases have several things in common so that when you are controlling one you are often controlling the other two as well. First all three fungi survive in the soil and on plant debris from last year's tomatoes and weeds. Second they all have spores splashed up into the lower leaves to start the disease. Third they all need moisture to cause disease.

Knowing these three things, there are several cultural practices that can significantly reduce the amount of disease from these three fungi.

1. Reduce the amount of fungi in your garden

a. Plant tomatoes where no tomatoes, potatoes, peppers, or eggplants have been for the past 3-4 years.

b. Completely remove old tomato plants from the garden at the end of the season and compost or bury the old vines.

c. If this is not possible, bury old vines in the garden so soil microorganisms can break down the plant material.

2. Keep tomato leaves as dry as possible

a. Mulch tomato plants with 3-4 inches of organic mulch like leaves, hay, or wood chips. This keeps water in the soil where roots can get it. Mulch also reduces humidity in the plant canopy.

b. Use drip irrigation, soaker hose, or direct water at the base of the plant.

c. Water early in the morning so that leaves dry quickly in the sun.

d. Stake or cage plants. Moisture is highest at the soil surface, supported tomato plants dry quicker and are less likely to have disease problems (Fig. 2).

e. Space plants far enough away from each other that air flows between plants.

3. Stop spores from splashing from soil to plant and from plant to plant

a. Mulch tomato plants with 3-4 inches of organic mulch like leaves, hay, or wood chips. This stops water drops from hitting the soil and splashing spores into the plant canopy

b. Prune heavily infected leaves off tomato plants and compost or throw them in the garbage. Never remove more than 1/3 of a plants leaves!

Even with good cultural practices, fungicides are sometimes necessary to protect tomatoes from fungal diseases. Using some basic IPM principles can reduce the number of sprays needed each year. First scout your tomato plants once a week. Look at the lower leaves (this is where infection typically starts) for leaf spots. Check them closely to make sure they are caused by a fungal disease and not something else (bacteria, insect feeding, soil particles etc.). If you are unsure visit a Master Gardener plant clinic for help (http://www.extension.umn.edu/yardandgarden/MG/mgclinics/mgclinic.html).

Do not apply any fungicide until disease is actually present. By checking on plants once a week you should catch the disease before it becomes a big problem. Leaves with leaf spots can be removed from the garden. Fungicide sprays will then prevent the fungi from moving higher in the plant.

Next think about the weather. The chance of fungal disease increases with an increase in moisture on leaf surfaces. According to TOMCAST, a disease forecasting system used by professional tomato growers, a day that is 79F or warmer must have 3 hours of continuous leaf wetness for new infections to start. That's why it is so important to keep plant leaves dry. Remember rain, dew, and irrigation all create wet leaves. If the tomato leaves are dry, fungicide applications may not be necessary at all. Professional tomato growers are able to cut the number of fungicide sprays in half by paying attention to leaf moisture.

If nature does not cooperate, and moisture and fungi prevail, several options exist to protect tomato leaves and fruit. Organic options include copper and Serenade garden defense. Serenade garden defense is a biological control bacteria that protects leaves from fungi. It is new to the market but is labeled for tomato early blight. Sulfur is another organic broad spectrum fungicide available, but use sulfur carefully with tomatoes as it can burn the leaves if applied at high temperatures or at rates above what is recommended on the label. Conventional options include products with Mancozeb or Chlorothalonil listed as the active ingredient. Whether organic or conventional, always read the label and follow the instructions before using any pest control product.

http://msucares.com/newsletters/pests/infobytes/19980504.htm

http://umaine.edu/ipm/ipddl/publications/5087e/

There are many other links to look at. It appears other fungicides besides copper are available.