Month: June 2010

A Blight on Basil

Yesterday’s post covered late blight on tomatoes, just confirmed in Connecticut. Today brings news of another blight. One that attacks basil … that’s right … basil. I’m just full of good news!

I missed the NPR story on basil blight earlier in the week, but caught the link from the CT NOFA (Northeast Organic Farming Association) Facebook fan page. Apparently the disease is a problem in New York, New Jersey, Ohio, and Florida. It acts and spreads much like late blight in tomatoes – via splashed soil and wind – so it is likely to impact gardeners in surrounding areas. It’s also known as basil downy mildew.

The solution should you find your carefully tended basil leaves beginning to tinge yellow? Inspect the underside of the leaves for spores – they look like tiny grayish/brown specs between the veins (check out photo links below. If you find basil blight, freeze or make pesto with all the healthy leaves and destroy the remaining plant residue.  I’m only guessing you should isolate infected plants in a sealed plastic bag for trash disposal – this is what you should do with late blight infected tomatoes. I also guess you should not compost diseased plants.

Vegetable MD on basil blight – photos, more info on the pathogen, and a reporting link should your basil develop blight.

Photos of basil blight.

basil seedlings1 basil seedlings2 It just so happens that I went a little crazy planting basil this year – we LOVE pesto. I have five varieties potted in numerous containers and planted amongst perennials; large-leaved Basilico Mostruoso, Italiano Classico, Basilico Finissimo Verde a Palla, a globe-shaped bushy plant, and Greek Mini Yevani, a small leaved Ocimum-type, and lemon basil. I’ve also given a good number of small transplants away. The prospect that some … many … all … could be wiped out by blight, as could my tomatoes, makes me downright queasy. My mouth waters for fresh tomato and basil salads – the perfect flavors of summer.

I have no experience with basil blight. I’d love to hear from anyone who has dealt with basil blight –how fast did it come on and spread?

Late Blight – The Sequel

It’s baaack … Connecticut Agricultural Experiment Station (CAES)recently issued the following:

-Alert for Late Blight of Tomato and Potato-

Late blight was identified on tomato plants from New Haven County on Thursday, 17 June 2010.  If you think you have seen late blight in your greenhouse, garden, or on volunteer potato plants, please contact The Plant Disease Information Office (203.974.8601).  You can also send or bring in samples for diagnosis.

Here’s a quick synopsis of the CAES late blight fact sheet:

This year tomatoes and potatoes are at high risk for  Phytophthora infestans (phyto is Greek for plant and phthora means destroyer), aka late blight, because of 2009’s widespread outbreak throughout Connecticut and the northeast. P. infestans overwinters in potato tubers.  Heavy rains, overhead watering, and soil disruption transports the pathogen to new plants. Infection becomes visible in 3 to 5 days and continues to grow at an alarming rate. Each individual lesion produces from 100,000 to 300,000 sporangia per day and each of these tiny buggers can go on to infect anew. Late blight can also infect other Solanaceae plants (eggplant and peppers for example) and ornamental hybrid petunias. Wind-blown sporangia can travel many, many miles.

CT’s Ag Station says the pathogen does not survive in soil, plant debris, or in tomato seeds. But when I listened in on a  2009 late blight teleconference by Cornell scientists they said late blight can survive in soils for as long as 8 years.  Either way, this is one plant destroya that lives up to its name – late blight is not to be messed with. Stopping/controlling it requires daily plant inspections and immediate removal and destruction (in sealed plastic bags) of all plant material. DO NOT COMPOST infected plants or fruit. I have not yet found a clear answer as to whether it is ok to burn infected plants in an outdoor fire pit. Please respond here if you know the answer.

Olive brown lesions on plant stems, 1/2 to 3/4 inch olive brown lesions – some with yellow margins – on leaves, and dark brown, rapidly expanding lesions on fruit are all signs of late blight. Similar fungal diseases on tomatoes  include Septoria lycopersici leaf spot, usually on lower leaves which then turn yellow and drop off, (I have leaf spot every year) and early blight, Alternaria solani, which causes dark brown/black 1/2 inch dead spots that enlarge to concentric rings (a bull’s eye). Follow this link for photos of tomatoes infected with late blight, Septoria, and early blight, and to read the entire tomato blight fact sheet.

More late blight info:

tomato1Don’t think you are safe because you missed last year’s outbreak and grew your plants from seed. An alert from CT NOFA (Northeast Organic Farming Association) confirms late blight in a backyard garden with no previous late blight problems and in tomatoes home-grown from seed. After a quick check in my gardens I can breath a brief sigh of relief – my tomatoes, so far, look healthy. Cherry tomatoes are beginning to fruit, and Pruden’s Purple, Roma, and Manyel plants are all in flower. But you can be sure I will check them daily for signs of late blight.