Section 18 Emergency Exemption for the Use of Tilt® on Grain Sorghum and Seed Sorghum for Control of Ergot in Kansas.

Kansas has once again been granted an emergency use permit for the application of Tilt fungicide to control ergot in grain sorghum.  The application instructions from the label include:

Make the first application of Tilt at or just prior to flowering. Make two (2) subsequent applications on a 5-7 day interval. Tilt must be applied at the rate of 4 fluid oz/A in a minimum of 15 gallons of water per acre when ground application equipment is utilized. Use a minimum of 5 gallons of water per acre by air. For improved efficacy in the management of ergot, the manufacturer recommends a minimum of ten (10) gallons of water per acre when aerial application equipment is utilized.

Keep in mind that control of ergot is primarily of importance to hybrid seed producers.  Ergot infection in the commercial grain crop is rare and usually occurs only in very late planted sorghum that will be blooming in September when cold weather sterility is more probable.  Because infection in even late planted sorghum is rare, fungicide control in commercial fields is generally not recommended. (Jardine)

                                                                                                  Spots on Apple and Pear Leaves

I’ve seen lots of examples lately of leaf spots on ornamental crabapple, pear, and related trees.  There are a couple of different leaf spots that appear at this time of year.  By the time you see these leaf symptoms the infection is long past and it is too late to try to control the disease.  These leaf spots will not cause spread to other leaves this year.
 

Cedar apple rust causes two types of lesions on apple.  You might remember large numbers of orange, alien-like structures on the red cedar (juniper) trees this year (Fig. 1).  Those fungal structures produce spores that infect apples, crabapples, pears, quince, and hawthorn (I’ll just say “apple” to abbreviate).  After incubation, the pathogen causes bright orange leaf spots on susceptible apples (Fig. 2). 

Eventually, orange cup-like structures form on the undersides of the leaves.  These structures produce spores that spread in the wind to infect red cedars and complete the life cycle.  On heavily infected apples trees the orange spores can shower out to form a visible powder on light-colored driveways or sidewalks.  If you touch a leaf or fruit with active sporulation structures the dusty orange spores on your fingers will make it look like you’ve been digging into a bag of cheese puffs.

Apple scab also causes leaf spots.  Scab first develops in early spring as circular, olive-green spots with a velvety texture.  Scab lesions can appear on the upper and lower surfaces of leaves and on the fruit (Fig. 4 and 5).  The spots turn dark green or brown with a rough, scaly texture.  The fungus only colonizes the surface, so lightly blemished fruit can still be eaten if you simply cut off the scabby part.

For both rust and scab the key time for fungicide management is in the spring when new infections are occurring.  Several captan, myclobutanil, and “multi-purpose” sprays are available for homeowners.  Be sure to check information on the labels.  The scab pathogen survives the winter in infected leaves, so with a manageable amount of trees it is possible to reduce the pathogen population for the next spring by raking up and removing leaves from under the trees. [Kennelly]  [Photos by Kennelly and N. Tisserat]