#Late blight tomato leaves skin#

Average monthly high temperature was 83 F and low was 68 F. There was only 2.01 inches of rain, with 1.08 inches falling over 28-30 August. With the exception of a lengthy rainstorm that started less than 3 days before these symptoms were seen (which is too short a time period for symptoms to develop after infection), weather conditions, being hot and dry during August in this area, did not seem to be favorable for late blight. Fruit were just starting to ripen in this late planting thus this is a total loss. These plants are too severely affected to be salvageable. Last fungicide application was copper 10 days earlier. These plants only had symptoms of Septoria leaf spot on a few lower leaves 3 days earlier. These images (below and the following thumbnails) were taken on 31 August 2009 when late blight was first observed on this farm. US23 was the pathogen strain responsible for the 2011 outbreak on Long Island.

The planting had not been sprayed with any fungicide. Pathogen growth likely was slowed by unfavorable high temperature, resulting in these uncharacteristic symptoms. A few spores of the late blight pathogen (sporangia) were found next to a major vein during careful inspection of lower leaf surfaces using a dissecting microscope, then examined with a compound microscope. Both leaf and fruit tissue tested positive for Phytophthora with an Agdia test kit.

#Late blight tomato leaves skin#

(See images below of fruit exterior and with skin peeled away.) No symptoms were seen on stems. View weather details.) Lacking a light green, wilted border that is typical with late blight, these symptoms more closely resemble those resulting from drought stress. (Daily highs were 86F to 101F and precipitation was 0.01 inch during previous 7 days in the specific location. The leaflets below illustrate the only leaf symptoms seen in an affected planting during a record-breaking high temperature period on Long Island, NY, in July 2011. Steve Johnson, University of Maine Cooperative Extension.) Symptoms of late blight on ripe fruit (below).īelow: Symptoms of late blight on ripe fruit (Photo courtesy Dr. Note fuzzy pathogen growth and spores, (below). Green fruit affected by late blight (below). Young plants can be infected before transplanting, showing stem lesions (below) … The brown spots on this tomato stem (below) are probably not due to late blight. Stem lesion with sporulation of the pathogen. These plants are too severely affected to be saved. Found on 25 July after an extensive heat wave ended with heavy rainfall.īelow: Plants with numerous initial symptoms of late blight. Click each image for larger viewsīelow: First symptoms on Long Island in 2013. Lesions (below) with growth and spores of the pathogen that developed while it was in a plastic bag over night.Ī single leaflet with a lesion is the first sign of late blight development in this garden.

Established lesions cannot be controlled, even with the most effective systemic fungicides that can be used by farmers with a pesticide license.įuzzy growth on the underside of leaf lesions (below) is produced by the pathogen under moist conditions and consists mostly of spores. And it is destructive as diseased tissue is killed quickly. The disease can be very explosive due to the quantity of spores produced and the quick disease cycle under cool, wet conditions. The spores can be dispersed by wind to healthy plant tissue, infect the healthy tissue if it is wet for a few hours, and within a few days produce a new lesion. The fungal growth on the stems and also on affected leaves consist of thousands of microscopic spores. Next two images: These dark brown lesions on stems, with white fungal growth developing under moist conditions, are characteristic of late blight. See close-up images of those lesions in following images. The primary symptoms are stem lesions between the second and top lines. There is an affected leaflet below the bottom trellis line. Image below shows initial symptoms of late blight on tomato in a garden.