7.2 Diseases - Time for Concern

7.2.1 DORMANT

7.2.1.1 Red Leaf Spot / Red Shoot Disease

Symptoms- This disease overwinters in infected leaves and shoots from the previous year. In the spring spindly shoots with red or yellow leaves emerge from infected runners. Later the undersides of leaves become covered with white powdery fungal spores. This disease is of little economic consequence.

Management Options

Guideline

Scouting/thresholds

None established.

Resistant cultivars

None established.

Cultural management

Promote drainage in the planting and avoid excessive nitrogen.

Conventional and

Organic products

Chemical control is not necessary.

7.2.2 BUD BREAK

7.2.2.1 Cottonball

Symptoms- This disease overwinters on the planting floor as hardened fungal structures referred to as sclerotia. These sclerotia are produced within infected fruit. Infection occurs when sclerotia germinate to produce mushrooms (apothecia) that eject infective spores. Spores infect shoot tissues, which subsequently produce secondary spores that infect flowers, which, in turn, lead to infected fruit. Resulting infected fruit become filled with thick cottony mycelium and often sclerotia as infection progresses. The cycle repeats itself each year as infected fruit with sclerotia fall of the plating floor.

Management Options

Guideline

Scouting/thresholds

None established.

Resistant cultivars

None established.

Cultural management

Harvest bushes clean, and remove residual sclerotia and infected fruit by re-flooding fields. Also consider promoting drainage in the beds and control moss as it serves as suitable environment for germinating sclerotia.

Conventional products

Apply fungicides only when sufficient disease was observed the previous year (e.g. 1 in 8 fruit infected). Make two fungicide applications beginning at bud break, and two additional applications beginning at 15% bloom.

A.    chlorothalonil - Equus DF (4.0 lbs/A). Apply at 10-14 day intervals.

B.    azoxystrobin - Abound 2.08F (10 fl oz./A). Apply beginning at 5-10% bloom and repeat as necessary at 7-14 day intervals.

C.    propiconazole - Orbit (4 fl oz./A) or Tilt (4 fl oz/A). Apply at bud break with a repeat application 14 days later. Make a third application in early bloom with a repeat application 14 days later.

Organic products

(May also be used in conventional production.)

A.    Streptomyces lydicus WYEC108- Actinovate AG (3-12 oz/A). Foliar applications: for best results apply with a spreader/sticker prior to onset of disease. Re-apply at 7-14 day intervals depending on disease pressure and environmental conditions.

7.2.3 BLOOM

7.2.3.1 Upright Dieback/Viscid Rot

Symptoms- This disease is not well understood, but it is believed that the pathogen survives in the uprights of the previous season (including healthy uprights). Infection of shoots occurs in spring. Infected uprights will first turn yellow at the tips. As infection progresses, they will become orange/bronze or brown and subsequently die. Developing berries on dead uprights will become desiccated and die. During bloom, latent infections may occur and mature fruit may rot late season or in storage. Infected fruit will become pale soft and slightly desiccated.

Management Options

Guideline

Scouting/thresholds

None established.

Resistant cultivars

Avoid Susceptible cultivars: ‘Searles’ ‘Howes’, and ‘Early Black’

Cultural management

Minimize factors affecting plant stress: drought, heat stress, winter and harvest injury,

Conventional products

Apply fungicides at between bud break and shoot elongation when shoots are ½ inch in length. Late season applications are ineffective for preventing dieback, but applications at bloom may prevent fruit rots.

A.    chlorothalonil - Equus DF (4.0 lbs/A). Apply at 10-14 day intervals.

Organic products

None known.

7.2.3.2 Early Fruit Rot

Symptoms- This disease overwinters in infected leaves and can affect flowers, shoots, and fruit. The majority of economic damage results from fruit infection. Fruit become infected during maturation in mid summer. Infections begin as tiny water soaked soft spots that enlarge to form brown concentric rings across the fruit surface. Fruit may also become infected in storage, but refrigeration stored fruit may prevent manifestation of latent infections. Infected flowers and immature fruit become black and desiccated and covered with fungal fruiting bodies.

Scouting/thresholds

None established

Resistant cultivars

None established.

Cultural management

Remove dead floating plant material at harvest, and promote drainage in beds.

Conventional products

Apply fungicides from early bloom to early fruit set.

A.    chlorothalonil - Equus DF (4.0 lbs/A). Apply at 10-14 day intervals.

B.    azoxystrobin - Abound 2.08F (10 fl oz/A). Apply at 7-14 day intervals.

Organic products

(May also be used in conventional production.)

A.    copper hydroxide- Nu Cop 50 WP or Nu Cop 50DF (8 lb/A). Make first application at late-bloom (mid-July), followed by 2 more applications at 10 – 14 day intervals, depending on disease severity.

7.2.4 HARVEST TO POST HARVEST

7.2.4.1 End Rot

Symptoms-This disease overwinters in mature woody tissues and plating debris. Infective spore are released from spring to harvest, but infection usually occurs during mild injury at harvest. Infections begin at the blossom end of the fruit and are soft and watery. Infected berries may become swollen with gas as the rot progresses, and eventually fruit becomes yellowish brown and desiccates.

Management Options

Guideline

Scouting/thresholds

None established.

Resistant cultivars

Cultivars ‘Beckwith’, ‘Bergman’, ‘Early Black’, ‘Howes’, ‘McFarlin’, ‘Pilgrim’, ‘Stevens’, and ‘Wilcox’ are reported to be resistant. Avoid Susceptible cultivars such as ‘Searles’ ‘Ben Lear’, and ‘Crowley’.

Cultural management

Avoid excessive nitrogen. Remove dead floating plant material at harvest. Promote drainage in the planting. Take care to avoid bruising fruit during harvest.

Conventional products

Apply fungicides at early and mid bloom, and during early fruit set.

A.    chlorothalonil - Equus DF (4.0 lbs/A). Apply at 10-14 day intervals.

Organic products

None known.