Apple Scab Resistant Crabapple Varieties

The cool, wet weather this spring has created ideal conditions for the development of apple scab on susceptible crabapple varieties. Scab is caused by the fungus Venturia inaequalis. Initial symptoms are small olive-green to black spots on the foliage. Eventually the leaves turn yellow and fall from the tree. Highly susceptible crabapple varieties may lose most of their foliage by midsummer. The heavy defoliation will weaken the trees somewhat, but will usually not kill them. The damage is mainly aesthetic. Heavily defoliated trees are unattractive.

Apple scab may be prevented by the application of fungicides, such as chlorothalonil, when growth first appears. Repeat at 7 to 10 day intervals until about the middle of June. Sanitation also plays an important role in controlling apple scab. Raking and destroying the leaves as they fall helps control the disease next season. The best way to avoid apple scab problems is to plant scab resistant varieties. The following crabapple varieties perform well in Iowa and also possess good to excellent resistance to apple scab.

Crabapples for Iowa

Species or Variety	Flower Color	Fruit Color	Ht/Wd	Tree Form
'Adams'	red	dark red	20/20	round
'Adirondack'	white	red	20/10	upright
'Amberina'	white	orange-red	12/12	upright-oval
'Anne E.'	white	red	10/10	weeping
'Autumn Glory'	white	orange-red	15/15	spreading
baccata 'Walters'	white	yellow-orange	15/15	round
'Bob White'	white	yellow	20/25	horizontal
'Candied Apple'	pink	dark red	15/15	weeping
'Centurion'	red	red	20/15	upright-spreading
'David'	white	red	15/15	round
'Donald Wyman'	white	red	20/20	round
'Doubloons'	white	yellow	12/10	upright-spreading
floribunda	pink white	yellow	20/25	horizontal
'Golden Raindrops'	white	yellow	20/15	upright-spreading
'Harvest Gold'	white	yellow	20/15	upright-spreading
'Indian Magic'*	pink	orange-red	15/15	round
'Indian Summer'	red	red	20/20	upright-spreading
'Jewelberry'	white	red	12/15	spreading
'Louisa'	pink	yellow	15/15	weeping
'Madonna'	white	red	20/15	upright-spreading
'Molten Lava'	white	orange-red	15/15	horizontal
'Pink Satin'	pink	dark red	15/15	rounded
'Prairifire'	red	dark red	20/20	upright-spreading
'Professor Sprenger'	white	orange-red	25/25	round
'Profusion'	red	dark red	20/20	upright-spreading
'Red Baron'	red	red	18/10	columnar
'Red Jade'	white	red	15/15	weeping
'Red Jewel'	white	red	18/12	upright-oval
'Red Swan'	white	red	15/15	weeping
sargentii	white	red	6/12	horizontal
'Sentinel'	white	red	15/10	upright
'Serenade'	white	orange	12/12	semi-weeping
'Silver Moon'	white	dark red	25/15	upright-oval
'Sinai Fire'	white	orange-red	15/15	weeping
'Snowdrift'*	white	orange	20/20	round
'Sugar Tyme'	white	red	20/20	round
'Winter Gold'	white	yellow	25/20	vase-shaped
x zumi 'Calocarpa'	white	red	15/20	horizontal
x zumi 'Winter Gem'	white	red	15/12	upright-spreading
x zumi 'Wooster'	white	orange-red	12/15	horizontal

* 'Indian Magic' and 'Snowdrift' possess good resistance to apple scab. However, they will lose considerable foliage whenweather conditions are ideal for scab.

Gardeners should avoid 'Almey,' 'Dorothea,' 'Hopa,' 'PinkPerfection,' 'Radiant,' 'Royalty,' and 'Vanguard.' All thesevarieties are highly susceptible to apple scab. 'Spring Snow' isone of the few crabapple varieties that produces little or nofruit. Unfortunately, it is also severely susceptible to applescab.

If a crabapple tree is in your future landscape plans,select a scab resistant variety at your local garden center ornursery.

This article originally appeared in the June 23, 1995 issue, pp. 1995 issue, pp. 92-93.