FFF 07-08

Crop conditions: Apple harvest is underway, with Galas 
looking very good, although crops are generally light. With 
a dry summer followed by rain close to harvest, some stem-
end splitting is showing up. Grape harvest is underway a 
bit earlier than normal, with compressed time between early 
and mid-season varieties. The southern half of the state 
missed the recent rains so fruit quality is holding up 
nicely. Areas that got rain on varieties close to harvest 
have seen some reduction in quality due to splitting and 
cracking. High temperatures have not been good for fall 
raspberry quality. Hopefully some relief will occur as we 
move into September.

Looking to buy fruit? With many growers having short crops 
this year, I have heard of a number of growers who are 
looking for sources of fruit. While it is not my intention 
to turn the Facts for Fancy Fruit newsletter into an 
advertising forum, the fruitveg and winegrape email lists 
are the perfect place for sharing this kind of information. 
In fact today I heard of a large apple grower from 
Minnesota with ample fruit supplies this year who is happy 
to supply Indiana growers. I have posted this information 
to the fruitveg list.  Look in the last issue of FFF for 
info on how to subscribe. Itās quick, easy and free. 
To subscribe, go to the Fruit and Vegetable Connection 
website, http://www.hort.purdue.edu/fruitveg and click on 
ćmail listsä from the menu on the left. From there click on 
either ćcommercial fruit and vegetableä or ćwine and grape 
productionä. From there you can sign yourself up and 
subscribe to the list. (Hirst)

Strawberry Fruit Bud Development:  The time to fertilize 
strawberries fields is upon us. Applications of 20 to 50 
pounds of nitrogen in mid August to September stimulate 
flower bud initiation during the fall months.  Rates depend 
upon amount of nitrogen supplied at renovation and plant 
vigor.  New fields with high vigor may not need additional 
nitrogen now, but most older fields should benefit.  
Irrigation during this time is also extremely important, if 
rainfall has not been sufficient.  We suggest about 1 inch 
per week.  Most of the northern half of the state received 
some much-needed rain recently, but in southern and central 
areas soils are quite dry. Keep up the irrigation on 
strawberries at this time to assure a good crop next year. 
(Bordelon)

Fall Herbicide Applications for Strawberries:  A number of 
herbicides can be used on strawberries during late summer 
and fall to prevent weed germination, kill emerged weeds, 
and provide residue control until the following spring.  
The key set of weeds you need to control during this period 
are fall germinating winter annuals such as chickweed, 
henbit, and shepherds purse.  You may also need to control 
wheat, oats, or rye that come from seed in the straw mulch 
that you apply for winter protection. 
	
Devrinol (napropamide) is a preemergence herbicide.  
It can inhibit rooting of daughter plants so it should be 
applied after early forming daughter plants have rooted.  
Late forming (after late August) daughter plants do not 
contribute to yield and Devrinol can be applied before 
these plants root.  Devrinol must be applied before winter 
annuals and small grains emerge.  Devrinol provides 
excellent control of small grains and some winter annuals 
such as chickweed.  Devrinol must be moved into the soil by 
cultivation or water after application. 
	
Dacthal (DCPA) is a preemergent herbicide that can be 
used in new plantings or immediately after renovation.  It 
provides good control of many grasses and some broadleafs 
such as purslane and lambsquarter.  Like Devrinol, it must 
be applied before weeds emerge. 
	
Sinbar (terbacil) is primarily a preemergent herbicide 
but it has some postemergence activity against small 
susceptible weeds.  Fall applications of Sinbar should only 
be applied after the strawberries are completely dominant.  
If Sinbar is applied to actively growing strawberries, 
injury can occur.  Cultivars differ in tolerance to Sinbar.  
In general, less vigorous cultivars have greater injury.  
Applications are most effective when applied to the soil 
and activated by rainfall or irrigation.  Sinbar provides 
excellent control of many winter annual weeds.  Fall 
applications of both Devrinol and Sinbar will persist to 
the following spring. 
	
Chateau (flumioxazin) is primarily a preemergent 
herbicide but has some postemergent activity against small 
susceptible weeds. Fall applications of Chateau should only 
be applied after the strawberries are completely dominant.  
If Chateau is applied to actively growing strawberries, 
injury can occur. Add 1% crop oil or 0.25% nonionic 
surfactant to improve postemergence control of small weeds.  
	
Poast (sethoxydim) is a postemergent, grass specific 
herbicide.  The grasses must be actively growing.  Thus 
Poast should be applied in late summer or early fall before 
plants become dormant.  Summer annual grasses, such as 
foxtails and crabgrass, will be killed by fall frosts, and 
do not require Poast applications for control.  Poast is 
more effective against annual than perennial grasses.  
Poast can be used in the fall to suppress perennial grasses 
such as quackgrass; control early emerging small grains, 
and kill winter annual grasses such as wild oats and downy 
brome. 
	
A systemic, postemergence broadleaf herbicide, 2,4-D 
amine can be applied when strawberries are dormant to 
control some winter annuals.  2,4-D provides good control 
of many mustards and shepherdspurse, but is not very 
effective against chickweed.  The herbicide should be 
applied to actively growing weeds.  Be careful of 2,4-D 
drift causing injury to non-target plants. Check the label 
as only a few formulations are labeled for strawberries.
	
Gramoxone Extra (paraquat) can be applied as a 
directed spray between strawberry rows, using shields to 
prevent contact with strawberry plants.  Gramoxone is a 
nonselective herbicide, so it will kill or severely injure 
strawberries it contacts.  Gramoxone is a restricted use 
pesticide and is extremely toxic to animals including 
humans.  It provides excellent control of annual grass and 
broadleaf weeds.  Gramoxone does not extensively 
translocate in plants so it does not control perennial 
weeds.  Weeds should be actively growing when Gramoxone is 
applied.  
	
The Midwest Small Fruit Pest Management Handbook has a 
chapter on weed management.  It is available on line at 
http://www.ag.ohio-state.edu/~sfgnet/ (Bordelon)

Perennial Weed Control:  Late summer and fall is an 
excellent time to control troublesome perennial weeds by 
spot spraying with suitable herbicides.  Perennial weeds 
tend to become established within the rows in fruit 
plantings because they are not fully controlled by the 
normal weed management program.  Once established, these 
plants can be difficult to eliminate. Glyphosate (e.g. 
Roundup) is a particularly good herbicide for controlling 
perennial weeds in the fall.  As perennial plants begin to 
slow growth and harden off for winter, carbohydrates are 
translocated to the roots for storage.  Fall applied 
systemic herbicides will be similarly transported to the 
root system which leads to excellent control.  Fall 
application works equally well on hard to control 
herbaceous perennial weeds such as thistle, dock, 
smartweed, and morning glory, as well as woody perennials 
such as poison ivy, Virginia creeper, multiflora rose, 
mulberry, blackberry and so on.  The plants do not have to 
be actively growing for good results but should have 
sufficient active leaf area to take up the herbicide.  
Check the manufacturerās product label for specific 
recommendations.  NOTE:  Desirable crop plants are also 
translocating carbohydrates to the roots and can be 
severely injured by fall applied systemic herbicides.  Be 
EXTREMELY CAREFUL when spot treating to avoid any contact 
with desirable plants. (Bordelon)

Black rot:  I recently received a submission of apples 
infected with black rot at the calyx end. Black rot, caused 
by the fungus Botryosphaeria obtusa, is the same fungus 
that causes frogeye leaf spot, black rot fruit decay, 
lovely cankers, and occasionally causes a calyx-end rot 
that appears in early summer÷like the sample I received 
that can be seen in the photos. The fungus can colonize any 
wound that penetrates the epidermis, including insect 
injuries. As lesions develop, they begin as reddish spots 
that darken to purple and are bordered by a red ring. A key 
symptom that distinguishes black rot from bitter rot is 
that there is usually only one spot per fruit. Eventually, 
the infected area changes color, becoming brown as it 
increases in size, or it may turn black. As this rotted 
area enlarges, concentric bands of brown and black develop 
with a surprising uniformity of width. The flesh of the 
decayed area remains firm and leathery. Eventually, the 
apple rots completely, dries, and shrivels into a mummy. 
Pycnidia, little erumpent pustules containing spores of the 
black rot fungus, appear on the surface of rotted tissue. 

 

Lesions of calyx-end rot caused by B. obtusa are usually 
dark brown to black and may completely surround the calyx 
or they may be offset to one side of the calyx. 
In orchards where inoculum levels are high and fungicide 
protection is lacking, B. obtusa can infect as soon as the 
bud scales begin to loosen, although infection of the 
flower sepals and/or fruit calyxes is more common. 
Unfortunately, growers are unaware of infection because the 
fungus usually remains quiescent; Symptoms of fruit decay 
develop only after fruit begins to ripen. All of the 
registered scab fungicides suppress B. obtusa, but the SI 
fungicides (Nova, Bayleton, Rubigan) and/or low rates of 
mancozeb fungicides (1 lb/100 gal) are barely effective. 
Captan and Topsin M provide the best protection against 
black rot infection and are recommended at petal fall in 
orchards where black rot fruit decay has been a problem in 
previous years. Strobilurins also provide some level of 
protection; Dave Rosenberg et al. 2000 found that 
treatments that included a strobilurin (Flint, Sovran, or 
Pristine) in the scab program provided better control of 
frogeye leaf spot (the foliar infection of Botryosphaeria 
obtusa) than did sprays of Nova-Dithane or Rubigan-Thiram. 
Although fruit rots were not evaluated in this study, I 
donāt think Iām going out on a limb to suggest anything 
controlling the foliar infection phase of this disease is 
probably controlling the fruit infecting stage as well.

Like many plant pathogens, by the time you find the problem 
it is too late for this year. However, sanitation in the 
form of mummy clean-up and cankered limb removal is 
something to consider during spring pruning. Apples that 
are mummified due to chemical thinning, or fire blighted 
twigs, serve as an easy site of colonization. Piles of 
prunings are another important reservoir of this disease.  
Prunings can be left if they are debarked during any sort 
of flail mowing. 

Cultivar susceptibility is definitely an issue, as well. 
Studies done by Alan Biggs and Stephen Miller in West 
Virginia ranked ĪOrinā, ĪPristineā, and ĪSunriseā as highly 
susceptible; ĪSuncrispā, ĪGinger Goldā, ĪSenshuā, 
ĪHoneycrispā, ĪPioneerMacā, ĪFortuneā, NY 75414, ĪArletā, 
ĪGolden Supremeā, ĪShizukaā, ĪCameoā, ĪSansaā, and ĪYatakaā 
as moderately susceptible; and least susceptible were 
ĪCrestonā, ĪGolden Deliciousā, ĪEnterpriseā, ĪGala 
Supremeā, ĪBraeburnā, ĪGoldRushā, and ĪFujiā.  Previous 
published rankings have included ĪRed Deliciousā, ĪEmpireā, 
and ĪCortlandā among the most susceptible cultivars to the 
black rot pathogen. From the NE-183 trial, only ĪGoldRushā, 
ĪEnterpriseā, and ĪGala Supremeā were more resistant than 
ćstandard varieties.ä

Last but not least, physiological stresses, especially 
drought stress, predispose trees to cankers caused by 
Botryosphaeria. This uptick in disease incidence may be 
just one more side effect of our spring freeze coupled with 
drought. As we head into Fall, careful observation of trees 
for cankers as a source of inoculum should be high on every 
growers list to mark for spring pruning and removal! 
(Beckerman)


Coming meetings:
Sept 13:  Fall Grape and Wine workshop. Details at 
http://www.foodsci.purdue.edu/research/labs/enology/ 
Contact Jill Blume (765-494-1749) for information.

Nov. 3:  Midwest Apple Improvement Association (MAIA) 
annual meeting.  Dawes Arboretum, Newark, OH.  For more 
information:  www.hort.purdue.edu/newcrop/maia

Jan. 28, 2008:  Mid American Ag and Hort Human Resource 
Conference in conjunction with the Indiana Horticultural 
Congress, Indianapolis, IN

Jan. 28-30, 2008: Indiana Horticultural Congress, Adamās 
Mark Hotel, Indianapolis. For more information: 
www.inhortcongress.org