Malheur Experiment Station Information for Sustainable Agriculture

The Shepody field was hand planted by leveling the fall bedded ground with a tractor mounted shovel, dropping the seed along the bottom of the bed, hilling up with tractor mounted shovels, then finishing the hilling process with hand shovels. This process dried out the soil so that the plots had to be irrigated in order to have enough moisture for adequate growth. Water was applied by furrow irrigation 7 days after planting.

The Russet Burbank trial was hand planted into fall bedded ground by opening the bed with a trenching shovel, dropping the seed to the proper depth, and pulling the shovel out, leaving the soil mostly undisturbed. The plots had adequate moisture for emergence and early growth without irrigation.

The seed was hand cut into approximately 2.0-oz pieces. The seed treatments were applied by putting the cut seed and the fungicide in a plastic bag and mixing the seed with the treatment. The Blocker treatment was applied to the Shepody potatoes by spraying the liquid down the planted furrow prior to covering the seed. The spray volume was 27.4 gpa and the spray was allowed to dry before the seed was covered.

Each plot in both trials was 50 ft long by one row wide. The trial was a randomized complete block design with four replications. The Shepody trial was planted on April 14-15 and the Russet Burbank trial was planted on April 28-29. Planting depth was 6-8 inches below the top of the hill, and the seed was spaced 12 inches apart. Plant emergence and early growth were measured. Rhizoctonia was measured on July 23 for Russet Burbank and September 2 for Shepody. The potatoes were hand dug and graded. Ten plants per plot were evaluated to determine the amount and severity of rhizoctonia infection.

The trial was harvested on September 2. Stems from 10 plants were rated for rhizoctonia infection. Lesions were scored as mild or severe (Table 2). The untreated check had significantly more infected stems than any of the treatments. Blocker alone had significantly more infected stems than the other treatments except Tops 5.0 and Tops MZ. Maxim had the highest percentage of rhizoctonia-free stems. Adding Blocker to Tops MZ increased the number of disease-free stems substantially, even though the number wasn't different statistically. Adding Blocker to Maxim did not decrease rhizoctonia infections. Maxim had the lowest number of severe lesions. Tops 5.0 and Blocker had a significantly higher amount of lesions than Maxim. There was no difference in stem numbers (Table 3).

Since Shepody potato processing contracts are based on total yield minus soil, rot, and undersized tubers, only total yield was measured. Total yield from the untreated check was significantly less than all other treatments except Blocker (Table 4). Blocker had significantly less in total yield than Maxim and Tops MZ + Blocker. Tops MZ + Blocker was not significantly better than the Tops MZ treatment. The treatments of Maxim plus the at-planting insecticide treatments (API – 1.5 DS, 1.7 DS) did not increase yield. Insect counts were made during the growing season, but insect populations were very low in all of the treatments, and counts were not significantly different.

The Russet Burbank trial included Tops 5.0, Tops MZ, Maxim, and the at-planting insecticide (API) added to Maxim at two rates. Blocker was not included in this trial. Emergence was delayed significantly by the Tops MZ treatment. Plant height was also less, though not significant, when measured on June 4, and there was a tendency to have reduced stem numbers with this treatment (Table 5).

Five plants per plot were harvested on July 23 (Table 6). Tops MZ had significantly fewer tuber numbers than Maxim + API 1.5 at the 90 percent confidence level. There were no significant differences in total tuber weight between treatments. There were highly significant differences between all of the treatments and the check for stems infected with severe Rhizoctonia. Severe rhizoctonia lesions were defined as lesions that had covered half the diameter of the stem. Maxim had significantly fewer severe lesions than Tops MZ. There were no differences in any of the treatments when both mild and severe lesions were considered.

Forty feet of row in each plot was harvested on October 1, graded, and weighed. There were no statistical differences in the treatments regarding yield (Table 7), but some trends seem apparent. Tops MZ had more large potatoes (>12 oz) but fewer small potatoes. One possible explanation is that rhizoctonia may have reduced the number of tubers enough to allow those that did survive to increase to a larger size. The main treatments with less rhizoctonia had smaller yields in the >12 oz category, probably because increased tuber numbers kept the tubers from sizing into the larger group. This is reflected in the higher yields in the 8–12 oz and 4–7.9 oz categories for Maxim.

Aphid counts were taken during the growing season, but the populations were so low that no determinations could be made on the efficacy of the planting insecticide seed treatments.

Blocker inhibited Shepody foliage growth early in the season. All of the seed treatments significantly increased yields of Shepody over the untreated check. Maxim and Tops MZ + Blocker both yielded significantly higher than Blocker applied alone on Shepody. Maxim was the best treatment for controlling severe rhizoctonia in both Shepody and Russet Burbank.

All of the seed treatments on Russet Burbank were better than the untreated check. The Maxim treatment had significantly fewer severe rhizoctonia lesions than the Tops MZ treatment. There were no yield differences among any of the treatments on Russet Burbank, but the untreated check consistently yielded lower in all of the yield categories.

Table 1. Plant height of Shepody potatoes as influenced by at-planting seed treatments, Ontario, Oregon, 1999.

Treatment		Application rate	Average plant height
			inches
Tops 5.0		0.5 lb/100 lb cut seed	9.4
Tops MZ		1.0 lb/100 lb cut seed	11.0
Maxim		0.5 lb/100 lb cut seed	9.7
Blocker		10 pints/acre	8.4
Maxim + API* 1.7 DS		0.5 lb/100 lb cut seed	10.1
Tops MZ + Blocker		0.5 lb/100 lb cut seed + 10 pints/acre	10.0
Maxim + Blocker		0.5 lb/100 lb cut seed + 10 pints/acre	9.9
Untreated Check			10.0
LSD (0.05)			1.1

*API = At-Planting Insecticide

Table 2. Rhizoctonia infection in Shepody potato stems as influenced by fungicide seed treatments on September 2, Ontario, Oregon, 1999.

Treatment		Application rate	Stems With rhizoctonia lesions	Number of Severe Rhizoctonia
			%	Lesions/10 plants
Tops 5.0		0.5 lb/100 lb cut seed	50.7	6.5
Tops MZ		1.0 lb/100 lb cut seed	46.4	3.8
Maxim		0.5 lb/100 lb cut seed	22.0	1.0
Blocker		10 pints/acre	54.8	5.0
Maxim +  API* 1.7 DS		0.5 lb/100 lb cut seed	32.9	2.0
Tops MZ + Blocker		0.5 lb/100 lb cut seed + 10 pints/acre	28.4	2.3
Maxim + Blocker		0.5 lb/100 lb cut seed + 10 pints/acre	28.9	4.3
Untreated Check			77.0	9.8
LSD (0.05)			20.7	3.3

*API = At-Planting Insecticide

Table 3. Stem numbers as influenced by seed piece treatments, Ontario, Oregon, 1999.

*API = At Planting Insecticide

Table 4. Total yield of Shepody potatoes as influenced by seed piece treatments, Ontario, Oregon, 1999.

* API = At-Planting Insecticide

Table 5. Stand count, plant height, and stem number on Russet Burbank potatoes with different seed treatments, Nyssa, Oregon, 1999.

Treatment	Application rate	Stand  count 5/26/99	Plant height 6/4/99	Stem number 7/23/99
		50 ft of row	Inches	5 plants/plot
Tops 5.0	0.5 lb/100 lb cut seed	40.0	5.9	2.7
Tops MZ	1.0 lb/100 lb cut seed	31.5	5.0	2.1
Maxim	0.5 lb/100 lb cut seed	43.0	6.5	2.3
Maxim + API* 1.7	0.5 lb/100 lb cut seed	36.8	6.2	2.5
Maxim + API* 1.5	0.5 lb/100 lb cut seed	40.5	6.6	2.9
Untreated Check		37.3	6.6	2.8
LSD (0.05)		5.3	n.s.	n.s.

*API = At-Planting Insecticide

Table 6. Tuber number, tuber weight, and rhizoctonia stem incidence in Russet Burbank potatoes with different seed treatments, Nyssa, Oregon, 1999.

Treatment	Ave. tuber number (5 plants)	Total tuber weight (5 plants)	Stems with at least 1 severe rhizoctonia lesion (5 plants)	Stems with mild or severe rhizoctonia lesions (5 plants)
				%
Tops 5.0	8.5	11.6	1.8	98
Tops MZ	6.5	10.7	4.0	93
Maxim	7.5	12.1	0.8	96
Maxim + API* 1.7	9.0	13.4	1.8	96
Maxim + API* 1.5	11.8	13.3	2.8	96
Untreated Check	7.5	11.5	7.3	100
LSD (.10)	2.9	n.s.		n.s.
LSD (.05)			3.1
LSD (.01)			4.3

*API = At-Planting Insecticide

Table 7. Effect of different seed treatments on yield of Russet Burbank potatoes, Nyssa, Oregon, 1999.

				---------Number Ones----------				Total	Total	Total
Treatment			>12 oz.		8–12 oz.	4–7.9 oz.		# 1's	# 2's	yield
			-----------------------------------------cwt/acre-----------------------------
Tops 5.0			131.7		136.5	118.3		386.5	155.8	542.3
Tops MZ			150.3		110.6	93.6		354.5	166.2	520.7
Maxim			118.8		125.0	117.4		361.2	158.3	519.5
Maxim + API* 1.7			127.6		125.6	120.7		373.9	141.9	515.8
Maxim + API* 1.5			114.9		129.9	120.1		364.9	176.3	541.2
Untreated Check			117.3		111.9	96.6		325.8	140.5	466.3
			n.s.		n.s.	n.s.		n.s.	n.s.	n.s.

*API = At-Planting Insecticide

Home

Crops

Weather

Potato Blight

Water Quality

Irrigation

Weeds

Search

MES Publications, MES Notice of events, Vegetation,Malheur County, Leslie Gulch,Succor Creek,Owyhee River,Local wildlife,Strawberry Mountain, Eagle Caps

Malheur Agricultural Experiment Station

Last updated  Tuesday July 30, 2002 .