Phytophthora-tolerant bell peppers

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.

Phytophthora on pepper
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.

Bell peppers
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.

For more information on commercial vegetable production, contact .(JavaScript must be enabled to view this email address) at 269-944-1477 ext. 207.

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