Phytophthora-tolerant bell peppers

Questions about this information? Contact us. April 02, 2013

Updated from an original article written by Ron Goldy.

Phytophthora capsici is a serious disease of many vegetable crops, including peppers. Fortunately, several commercially available bell peppers are genetically tolerant.

Phytophthora (Phytophthora capsici) can be a devastating disease of peppers. However, genetic tolerance has been incorporated in several commercial cultivars.

Phytophthora is a fungal disease capable of attacking pepper roots, shoots and fruit (Photo 1). Symptoms are often observed first where water gathers or flows. Disease then spreads from these areas as spores are carried on cultivation and other equipment or in water run-off. Phytophthora is long-lived in the soil, making it risky to plant a susceptible crop in fields having previous infections even after a significant length of time has passed.

Photo 1. Phytophthora capsici on pepper shoots and fruit.
Photo credit: Don Ferrin, Louisiana State University Agricultural Center, Bugwood.org

Pepper yield trials often include a combination of tolerant and non-tolerant lines. For growers who have Phytophthora, the performance of non-tolerant lines is irrelevant since the disease could potentially wipe out any increase in yield potential of susceptible varieties. For this reason, in 2012 a trial planted at the Southwest Michigan Research and Extension Center (SWMREC) in Benton Harbor, Mich., focused on testing only varieties that hold potential for growers with Phytophthora-infested fields.

The best performing entries across several traits were ACR285, ‘Aristotle’, ‘Karisma’, HMX1649, ‘Vanguard’ and PS09941819 (Table 1). ACR285 and ACX1003 were more pale-green in color and even though ACR285 was a top performer, the color may make it undesirable.

Table 1. Yield in bushels/acre and size grades of 16 Phytophthora capsici-tolerant bell peppers grown at SWMREC in 2012. Plant population was approximately 10,560 plants per acre.

Cultivar	Total Yield	Avg. No. 1 Fruit Wt.(gms)	Yield Jumbo	Yield Extra Large	Yield Large	Yield Med.	Yield No. 2	Yield Cull
ACR285	1747	167	137	210	556	371	339	134
FPP1814	1694	157	76	210	476	408	456	68
CSX32805	1688	149	83	161	412	530	418	8
Aristotle	1653	171	146	293	493	294	256	170
Karisma	1630	171	140	270	507	321	235	157
HMX1649	1612	167	208	264	438	334	250	118
Vanguard	1586	173	192	257	393	257	337	149
Paladin	1568	162	183	178	502	335	311	60
Lulton (ACX1003)	1562	133	11	95	509	492	350	106
nn030974	1561	171	140	250	463	354	278	76
PSO9941819	1558	176	211	337	426	267	201	116
nn030627	1503	170	131	229	442	349	264	87
Archimedes	1457	169	205	216	437	245	232	121
Enforcer (ACR294)	1403	147	8	91	342	408	408	146
Escalade	1387	150	34	119	435	407	345	48
Intruder	1368	158	45	163	430	395	247	88
lsd 0.05	290	10	106	81	117	94	104	58

Photo 2 was taken from the first harvest and amount of fruit shown is indicative of early yield potential.

Photo 2. Sixteen Phytophthora capsici-tolerant bell peppers grown at SWMREC in 2012. All left to right. Front row: FPP1814, ACR285, Enforcer (ACR294), ‘Escalade’. Second row: ‘Karisma’, ‘Vanguard’, HMX1649, CSX32805. Third row: Lulton (ACX1003), PS09941819, ‘Aristotle’, ‘Archimedes’. Back row: nn030974, nn030627, ‘Intruder’, ‘Paladin.

No selection was retested for Phytophthora-tolerance and no plant or fruit symptoms were observed in any trial plants or non-tolerant border plants. Since there are at least 14 Phytophthora races, it is possible to plant a “tolerant” cultivar only to have it show symptoms. This indicates the race in the soil is not one the cultivar can tolerate. Therefore, it would be of value for growers to identify what race they have and for seed companies to identify which race their pepper is tolerant to, something that is not currently done.

Alternatively, growers could fumigate or choose not to plant susceptible crops on that site again. Contact your local Michigan State University Extension county office for information on Phytophthora control in peppers and other vegetable crops.

Read a more in-depth report on this trial and other vegetable trials.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).

MSU Extension Vegetables