Early Blight (Alternaria solani)

[jcm05]

I have been seeing symptoms of early blight on my plants for the last few weeks. I wanted to show a photo I took of one lesion I found that is a perfect example of A. Solani infection. Symptoms normally show up on lower leaves first and progress upwards unlike Late Blight (P. Infestans) which can show anywhere on the plant first. Under heavy disease pressure the fungus can also infect stems and fruit as well. Early Blight lesions begin as small brown areas, similar to Septoria. The areas usually grow larger under the right conditions and are surrounded by a border of yellow host tissue (...again, unlike Late Blight). As the spots grow, "bullseye-like" concentric rings form much of the time within the brown tissue of the lesion. Heavily infected plants can become defoliated. The fungi can also survive on infected leaf tissue residue in or on the soil and be transferred by wind, rain or anything else that disturbs the soil where the fungus is present. It can also be transferred by seed. Yet another argument for soaking your saved seeds in a bleach solution.

[bluelacedredhead]

Nice Bulls-eye
JT, have you tried that fancy antifungal solution as yet?

[annie]

Excellent pic -- the best I've seen of this condition.

I rarely have this "bulls-eye" condition but rather seem to be inundated this year with bacterial spot that looks just like this:

agriculture.tennessee.edu/news//releases/2010/10-03-tomato.html

I've been removing all the affected leaves but can't keep up with it since it spreads quickly. My Brandywines, Opalkas, and Break O'Days have been hit hard by them. I think the Opalkas will survive for a while but probably not the BWs and BoDs.

I am glad to know what to look for in this other disease. Thanks.

[jcm05]

Jul 6, 2010 8:02:19 GMT -5 bluelacedredhead said:

Nice Bulls-eye
JT, have you tried that fancy antifungal solution as yet?

No, not as of yet. Weather conditions have turned very unfavorable for fungal disease recently. We have had hot dry weather now and have had not a drop of rain for weeks. Patches of EB here and there do not concern me.

[blackthumb]

I see no photo
Edit.
Ok now I see it.

[annie]

Well, I just discarded a tomato with the marring of those bullseye rings.

In the codes for tomato plant resistances, does the A mean Alternaria solani and Alternaria leaf spot? Are they the same disease?

[annie]

So if a tomato has a resistance to one alternaria disease, it may not be resistant to others, huh? Drat!

I've been looking for hybrid tomato varieties for next year that may have resistance to the common foliar diseases I've seen so far in my beds. Early blight for sure, and I'm not certain about at least one other one. The more letters the hybrids have, maybe that means they'll have the resistance needed (like Big Beef).

I'll be growing Abraham Lincoln next year, a new open-pollinated for me, reputed to have excellent disease resistance, though none of the literature I've seen says which one, and maybe Traveler 76, also claimed to have good disease resistance. I've been amazed at how well Goose Creek is holding up to the diseases in my garden -- I just removed all four Brandywines that succumbed to Early Blight, and they were entwined with the GCs. Still no disease apparent on the Goose Creeks that I can see, just a few yellowed leaves at the bottom of the plants. I'll certainly grow it again next year. Its taste gives Brandywine a run for the money by my taste buds!

The hybrids I'm thinking about are Bella Rosa, Bush Champion, and SunMaster. I'll add to the list from seeds I already have, probably Brandy Boy and Big Beef.

[annie]

Will someone take a look at the results of these field trials conducted by the University of Missouri Bradford Research Center near Columbia, Missouri?

www.hort.purdue.edu/fruitveg/rep_pres/MVVT2002/MVVT2002PDF/MO_Jett_02.pdf

Unless I've read the results wrong, in EVERY case, tomato varieties sprayed with Quadris and Bravo WS [described as eradicant or protective fungicides] performed less productively than the same varieties not sprayed with anything at all. The disease tested for was Early Blight, (Alternaria solani). This is a field evaluation of tomato varieties grown in Missouri.

I wonder if the results would be the same if Daconil, touted as a control for tomato fungal diseases, were used as the fungicide of choice.

[jcm05]

Thats not how I read it.

[amideutch]

Quadris is a systemic fungicide with the main ingredient being Azoxystrobin which is derived from mushrooms. It is systemic and is effective on several types of fungus. I use Azoxystrobin which is readily available in Germany and have had good results. Bravo is Daconil which is a protectant. I think annie needs to reread the report. Ami

[annie]

Well, I overstated the case a bit, but it looks to me as if the table shows that production is better of Grades 1 and 2 tomatoes for six of the unsprayed cultivars than for the sprayed cultivars. Take a look at this information and the last column, for instance, which shows production of marketable yield per acre and compare the sprayed and unsprayed results.



Maybe there are some other factors that explain the figures, but this is a quote from the introductory information:

Some cultivars seemed to possess very good tolerance to early blight. ‘BHN 543’, ‘Florida 91’, ‘HMX 0800’ and ‘Mountain Fresh’ produced significantly high yields even when they were not sprayed with fungicides (Table 1).

In addition to the cultivars mentioned above, Mountain Spring did better unsprayed [871 sprayed to 1115 unsprayed] as well as NC 96369 [662 sprayed to 1011 unsprayed].

Some of the opposite comparisons shown in the table are BHN444 [558 lbs per acre sprayed to 523 unsprayed], Celebrity [1139 sprayed to 941 unsprayed], Floralina [1021 sprayed to 1115 unsprayed], and HMX 0800 [1289 sprayed to 1115 unsprayed]. The differences are not as great as between the cultivars that did better when unsprayed. There are a couple more where the sprayed did better than the unsprayed.

Actually, six cultivars did better unsprayed, six that did better when sprayed, and one [Sun Chief] where the figures are the same.

Table 2, not reproduced here, shows their ranking of cultivars for EB tolerance, none of which is super-high if 9= excellent early blight tolerance as is indicated. Mountain Fresh is given the highest degree of EB tolerance [at level 5] of the cultivars tested followed by Florida 91 at level 4.7.

But what startled me was not the indication of EB tolerance by cultivars but rather the production comparison between the sprayed and unsprayed cultivars showing that developers are already on the road to creating tomato cultivars that seem to be at least incidentally tolerant of early blight without any spraying at all. Dr. Randy Gardner's contributions to developing cultivars that are tolerant to EB cannot be over-emphasized!

Ami, thanks for noting the ingredients in the two fungicides cited in the study.

[frogsleapfarm]

Aug 12, 2010 0:30:23 GMT -5 amideutch said:

Quadris is a systemic fungicide with the main ingredient being Azoxystrobin which is derived from mushrooms. It is systemic and is effective on several types of fungus. I use Azoxystrobin which is readily available in Germany and have had good results. Bravo is Daconil which is a protectant. I think annie needs to reread the report. Ami

I've been using Quadris this year, and it has been very effective in controlling Septoria

[amideutch]

I think a test with OP's would give a better picture of the effectiveness of fungicides as it is obvious most hybrid varieties have disease resistance bred into them. Plus that is what we grow, OP/Heirlooms. Ami